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interpretations of quantum mechanics ( qm ), or proposals for underlying theories, that attempt to present a definite realist picture, such as bohmian mechanics, require strong non - local effects. naively, these effects would violate causality and contradict special relativity. however if the theory agrees with qm the violation cannot be observed directly. here, we demonstrate experimentally such an effect : we steer the velocity and trajectory of a bohmian particle using a remote measurement. we use a pair of photons and entangle the spatial transverse position of one with the polarization of the other. the first photon is sent to a double - slit - like apparatus, where its trajectory is measured using the technique of weak measurements. the other photon is projected to a linear polarization state. the choice of polarization state, and the result, steer the first photon in the most intuitive sense of the word. the effect is indeed shown to be dramatic, while being easy to visualize. we discuss its strength and what are the conditions for it to occur.
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arxiv:1706.05757
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quantized single - electron transport driven by surface acoustic waves ( saw ) through a pinched - off narrow constriction is studied theoretically. long - range coulomb interaction causes the tunneling coupling between the two - dimensional electron gas ( 2deg ) and the moving minimum of the saw - induced potential to decay rapidly with time. the energy scale, associated with the characteristic time of this decay, controls both the width of the transition regions between the plateaus and the slope of the plateaus. this sets a limit for the accuracy of the quantization of acoustoelectric current at low temperature.
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arxiv:cond-mat/9909187
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we say that a linear code c over a field f is triangular representable if there exists a two dimensional simplicial complex $ \ delta $ such that c is a punctured code of the kernel ker $ \ delta $ of the incidence matrix of $ \ delta $ over f and there is a linear mapping between c and ker $ \ delta $ which is a bijection and maps minimal codewords to minimal codewords. we show that the linear codes over rationals and over gf ( p ), where p is a prime, are triangular representable. in the case of finite fields, we show that this representation determines the weight enumerator of c. we present one application of this result to the partition function of the potts model. on the other hand, we show that there exist linear codes over any field different from rationals and gf ( p ), p prime, that are not triangular representable. we show that every construction of triangular representation fails on a very weak condition that a linear code and its triangular representation have to have the same dimension.
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arxiv:1008.2937
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the first part of the paper is a brief overview of hindman ' s finite sums theorem, its prehistory and a few of its further generalizations, and a modern technique used in proving these and similar results, which is based on idempotent ultrafilters in ultrafilter extensions of semigroups. the second, main part of the paper is devoted to the topologizability problem of a wide class of algebraic structures called polyrings ; this class includes abelian groups, rings, modules, algebras over a ring, differential rings, and others. we show that the zariski topology of such an algebra is always non - discrete. actually, a much stronger fact holds : if $ k $ is an infinite polyring, $ n $ a natural number, and a map $ f $ of $ k ^ n $ into $ k $ is defined by a term in $ n $ variables, then $ f $ is a closed nowhere dense subset of the space $ k ^ { n + 1 } $ with its zariski topology. in particular, $ k ^ n $ is a closed nowhere dense subset of $ k ^ { n + 1 } $. the proof essentially uses a multidimensional version of hindman ' s finite sums theorem. the third part of the paper lists several problems concerning topologization of various algebraic structures, their zariski topologies, and related questions.
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arxiv:1810.01947
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the recent advent of topological states of matter spawned many significant discoveries. the quantum anomalous hall effect [ 1 - 3 ] is a prime example due to its potential for applications in quantum metrology [ 4, 5 ] as well as its influence on fundamental research into the underlying topological and magnetic states [ 6 - 11 ] and axion electrodynamics [ 2, 12 - 14 ]. here, we perform electronic transport studies on a ( v, bi, sb ) 2te3 ferromagnetic topological insulator nanostructure in the quantum anomalous hall regime. this allows us access to the dynamics of an individual ferromagnetic domain. the volume of the domain is estimated to be about 85 000 nm3, containing some 50 000 vanadium atoms, spread over a macroscopic distance of 115 nm. telegraph noise resulting from the magnetization fluctuations of this domain is observed in the hall signal. careful analysis of the influence of temperature and external magnetic field on the domain switching statistics provides evidence for quantum tunneling of magnetization [ 15 - 22 ] in a macrospin state. this ferromagnetic macrospin is not only the largest magnetic object in which quantum tunneling has been observed, but also the first observation of the effect in a topological state of matter.
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arxiv:2206.03972
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the magnetic structure of the iron monoarsenide feas is studied using first - principles calculations. we consider the collinear and non - collinear ( spin - spiral wave ) magnetic ordering and magnetic anisotropy. it is analitically shown that a magnetic triaxial anisotropy results in a sum of two spin - spiral waves with opposite directions of wave vectors and different spin amplitudes, so that the magnetic moments in two perpendicular directions do not equal each other.
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arxiv:1109.1924
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we present a new technique for detecting structure on mpc scales in the lyman - alpha forest. the technique is easy to apply in practice since it does not involve absorption line fitting but is rather based on the statistics of the transmitted flux. it identifies and assesses the statistical significance of regions of over - or underdense lyman - alpha absorption and is fairly insensitive to the quality of the data. using extensive simulations we demonstrate that the new method is significantly more sensitive to the detection of large - scale structure in the lyman - alpha forest than a traditional two - point correlation function analysis of fitted absorption lines.
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arxiv:astro-ph/9808082
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we give a partial answer to a question asked by eliashberg in one of his recent papers.
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arxiv:1905.00388
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generative diffusion models have achieved remarkable success in producing high - quality images. however, because these models typically operate in continuous intensity spaces - diffusing independently per pixel and color channel - they are fundamentally ill - suited for applications where quantities such as particle counts or material units are inherently discrete and governed by strict conservation laws such as mass preservation, limiting their applicability in scientific workflows. to address this limitation, we propose discrete spatial diffusion ( dsd ), a framework based on a continuous - time, discrete - state jump stochastic process that operates directly in discrete spatial domains while strictly preserving mass in both forward and reverse diffusion processes. by using spatial diffusion to achieve mass preservation, we introduce stochasticity naturally through a discrete formulation. we demonstrate the expressive flexibility of dsd by performing image synthesis, class conditioning, and image inpainting across widely - used image benchmarks, with the ability to condition on image intensity. additionally, we highlight its applicability to domain - specific scientific data for materials microstructure, bridging the gap between diffusion models and mass - conditioned scientific applications.
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arxiv:2505.01917
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in a recent paper [ arxiv : 0904. 2904 ] using a conjecture it is shown how one can calculate the effect of a weak stationary gravitational field on vacuum energy in the context of casimir effect in an external gravitational field treated in 1 + 3 formulation of spacetime decomposition.. in this article, employing quntum field theory in curved spacetime, we explicitly calculate the effect of a weak static gravitational field on virtual massless scalar particles in a casimir apparatus. it is shown that, as expected from the proposed conjecture, both the frequency and renormalized energy of the virtual scalar field are affected by the gravitational field through its index of refraction. this could be taken as a strong evidence in favour of the proposed conjecture. generalizations to weak { \ it stationary } spacetimes and virtual photons are also discussed.
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arxiv:1003.0614
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we present the first assessment, using hybrid pic simulations, of the role of non - linear landau damping in the process of self - generated scattering in a high $ \ beta $ plasma, conditions appropriate for cr scattering in the halo of the galaxy. this damping process manifests itself in the form of heating of the background plasma and reduction of the drift speed of crs that yet remains super - alfvenic. we also show that the damping leads to an inverse cascade process, consisting of producing non - resonant large scale modes, a novel result with many potential phenomenological implications.
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arxiv:2409.02230
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we have investigated the isoscalar giant monopole resonance ( gmr ) in the sn isotopes, using inelastic scattering of 400 - mev $ \ alpha $ - particles at extremely forward angles, including 0 deg. a value of - 550 \ pm 100 mev has been obtained for the asymmetry term, $ k _ \ tau $, in the nuclear incompressibility.
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arxiv:0709.3132
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we develop a characteristics based demand estimation framework for the marshallian demand system obtained by solving a budget - constrained constant elasticity of substitution ( ces ) utility maximization problem. from our marshallian ces demand system, we derive the same market share equation of berry ( 1994 ) ; berry, levinsohn, and pakes ( 1995 ) ' s characteristics based logit demand system. our ces demand estimation framework can accommodate zero predicted and observed market shares by conceptually separating the whether - to - buy decision and how - much - to - buy decision. furthermore, the estimator we suggest allows a tractable semiparametric estimation strategy that is flexible regarding the distribution of unobservable product characteristics. we apply our framework to scanner data on cola sales, where we show estimated demand curves can be upward sloping if zero market shares are not accommodated properly.
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arxiv:1511.05600
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we introduce projectq, an open source software effort for quantum computing. the first release features a compiler framework capable of targeting various types of hardware, a high - performance simulator with emulation capabilities, and compiler plug - ins for circuit drawing and resource estimation. we introduce our python - embedded domain - specific language, present the features, and provide example implementations for quantum algorithms. the framework allows testing of quantum algorithms through simulation and enables running them on actual quantum hardware using a back - end connecting to the ibm quantum experience cloud service. through extension mechanisms, users can provide back - ends to further quantum hardware, and scientists working on quantum compilation can provide plug - ins for additional compilation, optimization, gate synthesis, and layout strategies.
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arxiv:1612.08091
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photofission of actinides is studied in the region of nuclear excitation energies that covers the entire giant dipole resonance ( gdr ) region. the mass distributions of $ ^ { 238 } $ u photofission fragments have been explored theoretically for eight different endpoint bremsstrahlung energies from 11. 5 mev to 67. 7 mev which correspond to average photon energy of 9. 09 mev to 15. 90 mev. among these energies, the 29. 1 mev corresponds to the average photon energy of 13. 7 $ \ pm $ 0. 3 mev which coincides with gdr peak for $ ^ { 238 } $ u photofission. the integrated yield of $ ^ { 238 } $ u photofission as well as charge distribution of photofission products are calculated and its role in producing nuclei and their neutron - richness is investigated.
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arxiv:1511.08149
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there is a large ongoing research effort towards obtaining a quantum advantage in the solution of combinatorial optimization problems on near - term quantum devices. a particularly promising platform for testing and developing quantum optimization algorithms are arrays of trapped neutral atoms, laser - coupled to highly excited rydberg states. however, encoding combinatorial optimization problems in atomic arrays is challenging due to the limited inter - qubit connectivity given by their native finite - range interactions. here we propose and analyze a fast, high fidelity four - body rydberg parity gate, enabling a direct and straightforward implementation of the lechner - hauke - zoller ( lhz ) scheme and its recent generalization, the parity architecture, a scalable architecture for encoding arbitrarily connected interaction graphs. our gate relies on onetime - optimized adiabatic laser pulses and is fully programmable by adjusting two hold - times during operation. we numerically demonstrate an implementation of the quantum approximate optimization algorithm ( qaoa ) for a small scale test problem. our approach allows for efficient execution of variational optimization steps with a constant number of system manipulations, independent of the system size, thus paving the way for experimental investigations of qaoa beyond the reach of numerical simulations.
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arxiv:2106.02663
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we study a class of flux compactifications that have all the moduli stabilised, a high ( gut ) string scale and a low ( tev ) gravitino mass that is generated dynamically. these non - geometric compactifications correspond to type ii string theories on su ( 3 ) xsu ( 3 ) structure orientifolds. the resulting superpotentials admit, excluding non - perturbative effects, supersymmetric minkowski vacua with any number of moduli stabilised. we argue that non - perturbative effects are present and introduce terms in the superpotential that are exponentially suppressed by the same moduli that appear perturbatively. these deform the supersymmetric minkowski vacua to supersymmetric ads vacua with an exponentially small gravitino mass. the resulting vacua allow for low scale supersymmetry breaking which can be realised by a number of mechanisms.
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arxiv:0707.1595
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x > a $ ) is simple. our results elucidate the relationship between brf and log - normal distributions when $ a = b $ and explain why the brf is ubiquitous and versatile. based on the pdf, we suggest a quick way to elucidate if a real data set follows a one - sided power - law, a log - normal, a two - sided power - law or a brf. we illustrate our results with two examples : urban populations and financial returns.
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arxiv:1910.05364
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in this paper, we analyze period color and amplitude color relations at minimum, mean and maximum $ v $ band light for 6391 rrab stars in the large magellanic cloud obtained by the macho project. specifically, we find that color and amplitude are nearly independent of period at minimum light but that there exists a definite relation between period and color and amplitude and color at maximum light. these two properties are easily explained by the application of the stefan boltzmann law and the interaction of the photosphere and hydrogen ionization front at minimum light. when we examine the slope of the period color relation as a function of phase, we find that the slope varies significantly with phase and is small for a wide range of phases around minimum light. this suggests that another factor that needs to be considered when trying to understand rr lyrae observed properties is their behavior at different phases during a pulsation cycle.
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arxiv:astro-ph/0407485
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we show that for any nontrivial knot $ k $ and any natural number $ n $ there is a diagram $ d $ of $ k $ such that the unknotting number of $ d $ is greater than or equal to $ n $. it is well known that twice the unknotting number of $ k $ is less than or equal to the crossing number of $ k $ minus one. we show that the equality holds only when $ k $ is a $ ( 2, p ) $ - torus knot.
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arxiv:0805.3174
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channel and spatial attention mechanism has proven to provide an evident performance boost of deep convolution neural networks ( cnns ). most existing methods focus on one or run them parallel ( series ), neglecting the collaboration between the two attentions. in order to better establish the feature interaction between the two types of attention, we propose a plug - and - play attention module, which we term " cat " - activating the collaboration between spatial and channel attentions based on learned traits. specifically, we represent traits as trainable coefficients ( i. e., colla - factors ) to adaptively combine contributions of different attention modules to fit different image hierarchies and tasks better. moreover, we propose the global entropy pooling ( gep ) apart from global average pooling ( gap ) and global maximum pooling ( gmp ) operators, an effective component in suppressing noise signals by measuring the information disorder of feature maps. we introduce a three - way pooling operation into attention modules and apply the adaptive mechanism to fuse their outcomes. extensive experiments on ms coco, pascal - voc, cifar - 100, and imagenet show that our cat outperforms existing state - of - the - art attention mechanisms in object detection, instance segmentation, and image classification. the model and code will be released soon.
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arxiv:2212.06335
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we present the first lattice simulation to investigate the nature of multi - stream inflation. the simulation confirms the physical picture of multi - stream inflation, and with new findings in parameter space and field behaviors. our simulation shows that gradient energy plays a significant role in multi - stream inflation. for a double field potential with a shifted gaussian barrier, bifurcation probability is controlled by the shift distance with an error function relation. the bubbles created by bifurcation tend to be more spherical as bifurcation probability decreases. also, the bifurcation is more likely to introduce oscillations of field values inside the bubbles than outside.
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arxiv:2110.05268
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we find new exact analytical solutions in three - dimensional gravity applying the minimal geometric deformation approach in a cloud of strings.
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arxiv:1810.08830
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in this paper, starting from a quantum master equation, we discuss the interaction between two negatively charged nitrogen - vacancy color centers in diamond via exciton - polaritons propagating in a two - dimensional transition metal dichalcogenide layer in close proximity to a diamond crystal. we focus on the optical 1. 945 ev transition and model the nitrogen - vacancy color centers as two - level ( artificial ) atoms. we find that the interaction parameters and the energy levels renormalization constants are extremely sensitive to the distance of the nitrogen - vacancy centers to the transition metal dichalcogenide layer. analytical expressions are obtained for the spectrum of the exciton - polaritons and for the damping constants entering the lindblad equation. the conditions for occurrence of exciton mediated superradiance are discussed.
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arxiv:2009.12194
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can be performed. this version of a universe is defined to be any set for which the following axioms hold : x β u β u { \ displaystyle x \ in u \ in u } implies x β u { \ displaystyle x \ in u } u β u { \ displaystyle u \ in u } and v β u { \ displaystyle v \ in u } imply { u, v }, ( u, v ), and u Γ v β u { \ displaystyle u \ times v \ in u }. x β u { \ displaystyle x \ in u } implies p x β u { \ displaystyle { \ mathcal { p } } x \ in u } and βͺ x β u { \ displaystyle \ cup x \ in u } Ο β u { \ displaystyle \ omega \ in u } ( here Ο = { 0, 1, 2,... } { \ displaystyle \ omega = \ { 0, 1, 2,... \ } } is the set of all finite ordinals. ) if f : a β b { \ displaystyle f : a \ to b } is a surjective function with a β u { \ displaystyle a \ in u } and b β u { \ displaystyle b \ subset u }, then b β u { \ displaystyle b \ in u }. the most common use of a grothendieck universe u is to take u as a replacement for the category of all sets. one says that a set s is u - small if s βu, and u - large otherwise. the category u - set of all u - small sets has as objects all u - small sets and as morphisms all functions between these sets. both the object set and the morphism set are sets, so it becomes possible to discuss the category of " all " sets without invoking proper classes. then it becomes possible to define other categories in terms of this new category. for example, the category of all u - small categories is the category of all categories whose object set and whose morphism set are in u. then the usual arguments of set theory are applicable to the category of all categories, and one does not have to worry about accidentally talking about proper classes. because grothendieck universes are extremely large, this suffices in almost all applications. often when working with grothendieck universes, mathematicians assume the axiom of universes : "
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https://en.wikipedia.org/wiki/Universe_(mathematics)
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the paradigm of tabled logic programming ( tlp ) is now supported by a number of prolog systems, including xsb, yap prolog, b - prolog, mercury, als, and ciao. the reasons for this are partly theoretical : tabling ensures termination and optimal known complexity for queries to a large class of programs. however the overriding reasons are practical. tlp allows sophisticated programs to be written concisely and efficiently, especially when mechanisms such as tabled negation and call and answer subsumption are supported. as a result tlp has now been used in a variety of applications from program analysis to querying over the semantic web. this paper provides a survey of tlp and its applications as implemented in xsb prolog, along with discussion of how xsb supports tabling with dynamically changing code, and in a multi - threaded environment.
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arxiv:1012.5123
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motivated by ideas of fractionalization and intrinsic topological order in bosonic models with short - range interactions, we consider similar phenomena in formal lattice gauge theory models. specifically, we show that a compact quantum electrodynamics ( cqed ) can have, besides the familiar coulomb and confined phases, additional unusual confined phases where excitations are quantum lines carrying fractions of the elementary unit of electric field strength. we construct a model that has $ n $ - tupled monopole condensation and realizes $ 1 / n $ fractionalization of the quantum faraday lines. this phase has another excitation which is a $ z _ n $ quantum surface in spatial dimensions five and higher, but can be viewed as a quantum line or a quantum particle in four or three spatial dimensions respectively. these excitation have statistical interactions with the fractionalized faraday lines ; for example, in three spatial dimensions, the particle excitation picks up a berry phase of $ e ^ { i2 \ pi / n } $ when going around the fractionalized faraday line excitation. we demonstrate the existence of this phase by monte carlo simulations in ( 3 + 1 ) space - time dimensions.
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arxiv:1408.3146
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light detection and ranging ( lidar ) is an essential sensor technology for autonomous driving as it can capture high - resolution 3d data. as 3d object detection systems ( od ) can interpret such point cloud data, they play a key role in the driving decisions of autonomous vehicles. consequently, such 3d od must be robust against all types of perturbations and must therefore be extensively tested. one approach is the use of adversarial examples, which are small, sometimes sophisticated perturbations in the input data that change, i. e., falsify, the prediction of the od. these perturbations are carefully designed based on the weaknesses of the od. the robustness of the od cannot be quantified with adversarial examples in general, because if the od is vulnerable to a given attack, it is unclear whether this is due to the robustness of the od or whether the attack algorithm produces particularly strong adversarial examples. the contribution of this work is hi - alps - - hierarchical adversarial - example - based lidar perturbation level system, where higher robustness of the od is required to withstand the perturbations as the perturbation levels increase. in doing so, the hi - alps levels successively implement a heuristic followed by established adversarial example approaches. in a series of comprehensive experiments using hi - alps, we quantify the robustness of six state - of - the - art 3d od under different types of perturbations. the results of the experiments show that none of the od is robust against all hi - alps levels ; an important factor for the ranking is that human observers can still correctly recognize the perturbed objects, as the respective perturbations are small. to increase the robustness of the od, we discuss the applicability of state - of - the - art countermeasures. in addition, we derive further suggestions for countermeasures based on our experimental results.
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arxiv:2503.17168
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we study the geodesic flow on the global holomorphic sections of the bundle $ \ pi : { ts } ^ 2 \ to { s } ^ 2 $ induced by the neutral k \ " ahler metric on the space of oriented lines of $ { \ bbb { r } } ^ 3 $, which we identify with $ { ts } ^ 2 $. this flow is shown to be completely integrable when the sections are symplectic and the behaviour of the geodesics is described.
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arxiv:math/0602512
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in this note, we obtain a logarithmic vanishing theorem on certain weakly pseudoconvex k \ " ahler manifolds. it is a generalization of norimatsu ' s result on compact k \ " ahler manifolds. as a direct corollary, we obtain relative vanishing theorems of certain direct image sheaves.
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arxiv:2201.11458
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in this article with the help of the inverse function of the singular moduli we evaluate the rogers ranmanujan continued fraction and his first derivative.
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arxiv:1011.3521
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for a reduction in environmental pollution and dependency on petroleum, electric vehicles ( ev ) present an advantageous alternative to traditionally fossil - fuel powered automobiles. rapid growth in the number of evs requires an urgent need to develop an adequate charging station infrastructure to stimulate and facilitate their usage. due to restricted investments in the development of a sufficient infrastructure, locations have to be chosen deliberately. in this paper, three extensions considering different objectives and various constraints to the deterministic flow refuelling location problem ( dfrlp ), described 2017 by de vries and duijzer, are introduced. in the first extension we ask how many charging stations ( cs ) are necessary to cover a pre - specified number of evs and therefore exchange the original objective function for a minimizing cost function. secondly, our research shows that, when considering location - dependent construction costs, results heavily depend on the relations of said cost differences. tests for different cost scenarios are carried out and policy implications are discussed. in the last extension, we consider the capacity of a cs to be limited. the dfrlp assumes an unlimited capacity, meaning it is always possible to refuel all evs at all css, where they stop. in our model the capacity is put into relation to the total sum of demands generated by all evs, passing a particular cs, which means that our model determines the placement and the sizes of all css simultaneously. finally, all extensions are evaluated using benchmarks instances based on test instances from the literature.
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arxiv:2109.14358
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we have analyzed xmm - newton observations of the high energy peaked blazar, pks 2155 - 304, made on 24 may 2002 in the 0. 3 - 10 kev x - ray band. these observations display a mini - flare, a nearly constant flux period and a strong flux increase. we performed a time - resolved spectral study of the data, by dividing the data into eight segments. we fitted the data with a power - law and a broken power - law model, and in some of the segments we found a noticeable spectral flattening of the source ' s spectrum below 10 kev. we also performed time - resolved cross - correlation analyses and detected significant hard and soft lags ( for the first time in a single observation of this source ) during the first and last parts of the observation, respectively. our analysis of the spectra, the variations of photon - index with flux as well as the correlation and lags between the harder and softer x - ray bands indicate that both the particle acceleration and synchrotron cooling processes make an important contribution to the emission from this blazar. the hard lags indicate a variable acceleration process. we also estimated the magnetic field value using the soft lags. the value of the magnetic field is consistent with the values derived from the broad - band sed modeling of this source.
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arxiv:1510.02817
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we consider a class of extremal and non - extremal four - dimensional black - hole solutions occuring in toroidally compactified heterotic string theory, whose ten - dimensional interpretation involves a kaluza - klein monopole and a five - brane. we show that these four - dimensional solutions can be connected to extremal and non - extremal two - dimensional heterotic black - hole solutions through a change in the asymptotic behaviour of the harmonic functions associated with the kaluza - klein monopole and with the five - brane. this change in the asymptotic behaviour can be achieved by a sequence of s and t - s - t duality transformations in four dimensions. these transformations are implemented by performing a reduction on a two - torus with lorentzian signature. we argue that the same mechanism can be applied to extremal and non - extremal black - hole solutions in the fhsv model.
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arxiv:hep-th/9806036
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we use the recently - constructed explicit duality transformation that relates a rotating anti - d6 - d4 - d2 - d0 black hole solution to a rotating m5 - m2 - p black string to construct a non - supersymmetric black ring in taub - nut that has two angular momenta, as well as m2 charges and m5 dipole moments. this is the first black ring solution that has both dipole charges and rotation along the s ^ 2 of the horizon, and hence can be thought of as the " pomeransky - senkov " version of the m5 - m2 black ring in taub - nut. its physics should provide a testing ground for the applicability of the blackfold approach to charged rotating black branes, and should elucidate the phase space of charged dipole rings in various backgrounds.
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arxiv:1104.0016
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young massive stellar clusters are extreme environments and potentially provide the means for efficient particle acceleration. indeed, they are increasingly considered as being responsible for a significant fraction of cosmic rays ( crs ) accelerated within the milky way. westerlund 1, the most massive known young stellar cluster in our galaxy is a prime candidate for studying this hypothesis. while the very - high - energy $ \ gamma $ - ray source hess j1646 - 458 has been detected in the vicinity of westerlund 1 in the past, its association could not be firmly identified. we aim to identify the physical processes responsible for the $ \ gamma $ - ray emission around westerlund 1 and thus to better understand the role of massive stellar clusters in the acceleration of galactic crs. using 164 hours of data recorded with the high energy stereoscopic system ( h. e. s. s. ), we carried out a deep spectromorphological study of the $ \ gamma $ - ray emission of hess j1646 - 458. we furthermore employed h i and co observations of the region to infer the presence of gas that could serve as target material for interactions of accelerated crs. we detected large - scale ( $ \ sim 2 ^ \ circ $ diameter ) $ \ gamma $ - ray emission with a complex morphology, exhibiting a shell - like structure and showing no significant variation with $ \ gamma $ - ray energy. the combined energy spectrum of the emission extends to several tens of tev, and is uniform across the entire source region. we did not find a clear correlation of the $ \ gamma $ - ray emission with gas clouds as identified through h i and co observations. we conclude that, of the known objects within the region, only westerlund 1 can explain the bulk of the $ \ gamma $ - ray emission. several cr acceleration sites and mechanisms are conceivable, and discussed in detail. ( abridged )
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arxiv:2207.10921
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the protoplanetary disks of herbig ae stars eventually dissipate leaving a tenuous debris disk comprised of planetesimals and dust, as well as possibly gas and planets. this paper uses the properties of 10 - 20myr a star debris disks to consider the protoplanetary to debris disk transition. the physical distinction between these two classes is argued to rest on the presence of primordial gas in sufficient quantities to dominate the motion of small dust grains ( not the secondary nature of the dust or its level of stirring ). this motivates an observational classification based on the dust spectrum, empirically defined so that a star debris disks require fractional excesses < 3 at 12um and < 2000 at 70um. we also propose a hypothesis to test, that the main sequence planet / planetesimal structures are already in place ( but obscured ) during the protoplanetary disk phase. this may be only weakly true if planetary architectures change until frozen during disk dispersal, or completely false if planets and planetesimals form during disk dispersal. five steps in the transition are discussed : ( i ) carving an inner hole to form a transition disk ; ( ii ) depletion of mm - sized dust in outer disk, noting the importance of determining whether this mass ends up in planetesimals or is collisionally depleted ; ( iii ) final clearing of inner regions, noting that many mechanisms replenish moderate hot dust levels at later phases, and likely also operate in protoplanetary disks ; ( iv ) disappearence of gas, noting recent discoveries of primordial and secondary gas in debris disks that highlight our ignorance and its impending enlightenment by alma ; ( v ) formation of ring - like planetesimal structures, noting these are shaped by interactions with planets, and that the location of planetesimals in protoplanetary disks may be unrelated to the dust concentrations therein that are set by gas interactions.
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arxiv:1412.5598
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using three independent directions we estimate that the fraction of type ia supernovae ( sne ia ) exploding inside planetary nebulae ( pne ), termed snips, is at least ~ 20 %. our three directions are as follows. ( i ) taking the variable sodium absorption lines in some sn ia to originate in a massive circumstellar matter ( csm ), as has been claimed recently, we use the results of sternberg et al. ( 2014 ) to imply that > ~ 20 % of sn ia occur inside a pn ( or a pn descendant ), hence classify them as snips. ( ii ) we next use results that show that whenever there are hydrogen lines in sn ia the hydrogen mass in the csm is large ( > 1 m _ sun ), hence the explosion is a snip. we make the simplest assumption that the probability for explosion is constant in time for up to about 10 ^ 5 yrs after the merger of the core with the white dwarf ( wd ) in the frame of the core - degenerate scenario. this results with at least few x10 of sne ia that may have a snip origin. ( iii ) we examine the x - ray morphologies of 13 well - resolved close - by sn remnants ( snrs ) ia and derive a crude upper limit, according to which 10 - 30 % of all snrs ia possess opposite ear - like features, which we take as evidence of snip origin. our results, together with several other recent results, lead us to conclude that the two scenarios most contributing to sne ia are the core degenerate and the double degenerate scenarios. together these two account for > 95 % of all sne ia.
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arxiv:1409.0780
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multirate methods have been used for decades to temporally evolve initial - value problems in which different components evolve on distinct time scales, and thus use of different step sizes for these components can result in increased computational efficiency. generally, such methods select these different step sizes based on experimentation or stability considerations. for problems that evolve on a single time scale, adaptivity approaches that strive to control local temporal error are widely used to achieve numerical results of a desired accuracy with minimal computational effort, while alleviating the need for manual experimentation with different time step sizes. however, there is a notable gap in the publication record on the development of adaptive time - step controllers for multirate methods. in this paper, we extend the single - rate controller work of gustafsson ( 1994 ) to the multirate method setting. specifically, we develop controllers based on polynomial approximations to the principal error functions for both the " fast " and " slow " time scales within multirate infinitesimal ( mri ) methods. we additionally investigate a variety of approaches for estimating the errors arising from each time scale within mri methods. we then numerically evaluate the proposed multirate controllers and error estimation strategies on a range of multirate test problems, comparing their performance against an estimated optimal performance. through this work, we combine the most performant of these approaches to arrive at a set of multirate adaptive time step controllers that robustly achieve desired solution accuracy with minimal computational effort.
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arxiv:2202.10484
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this study investigates the effectiveness of genetic algorithms ( gas ) in solving both linear and nonlinear systems of equations, comparing their performance to traditional methods such as gaussian elimination, newton ' s method, and levenberg - marquardt. the ga consistently delivered accurate solutions across various test cases, demonstrating its robustness and flexibility. a key advantage of the ga is its ability to explore the solution space broadly, uncovering multiple sets of solutions - - a feat that traditional methods, which typically converge to a single solution, cannot achieve. this feature proved especially beneficial in complex nonlinear systems, where multiple valid solutions exist, highlighting the ga ' s superiority in navigating intricate solution landscapes.
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arxiv:2409.16958
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we present optical integral field spectroscopy of the circum - nuclear gas of the seyfert 2 galaxy ngc 1386. the data cover the central 7 $ ^ { \ prime \ prime } \ times 9 ^ { \ prime \ prime } $ ( 530 $ \ times $ 680 pc ) at a spatial resolution of 0. 9 " ( 68 pc ), and the spectral range 5700 - 7000 \ aa \ at a resolution of 66 km s $ ^ { - 1 } $. the line emission is dominated by a bright central component, with two lobes extending $ \ approx $ 3 $ ^ { \ prime \ prime } $ north and south of the nucleus. we identify three main kinematic components. the first has low velocity dispersion ( $ \ bar \ sigma \ approx $ 90 km s $ ^ { - 1 } $ ), extends over the whole field - of - view, and has a velocity field consistent with gas rotating in the galaxy disk. we interpret the lobes as resulting from photoionization of disk gas in regions where the agn radiation cones intercept the disk. the second has higher velocity dispersion ( $ \ bar \ sigma \ approx $ 200 km s $ ^ { - 1 } $ ) and is observed in the inner 150 pc around the continuum peak. this component is double peaked, with redshifted and blueshifted components separated by $ \ approx $ 500 km s $ ^ { - 1 } $. together with previous hst imaging, these features suggest the presence of a bipolar outflow for which we estimate a mass outflow rate of $ \ mathrm { \ dot m } \ gtrsim $ 0. 1 m $ _ { \ odot } $ yr $ ^ { - 1 } $. the third component is revealed by velocity residuals associated with enhanced velocity dispersion and suggests that outflow and / or rotation is occurring approximately in the equatorial plane of the torus. a second system of velocity residuals may indicate the presence of streaming motions along dusty spirals in the disk.
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arxiv:1504.05089
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the jamming scenario of disordered media, formulated about 10 years ago, has in recent years been advanced by analyzing model systems of granular media. this has led to various new concepts that are increasingly being explored in in a variety of systems. this chapter contains an introductory review of these recent developments and provides an outlook on their applicability to different physical systems and on future directions. the first part of the paper is devoted to an overview of the findings for model systems of frictionless spheres, focussing on the excess of low - frequency modes as the jamming point is approached. particular attention is paid to a discussion of the cross - over frequency and length scales that govern this approach. we then discuss the effects of particle asphericity and static friction, the applicability to bubble models for wet foams in which the friction is dynamic, the dynamical arrest in colloids, and the implications for molecular glasses.
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arxiv:1006.2365
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black hole production in elementary particle collisions is among the most promising probes of large extra spacetime dimensions. studies of black holes at particle colliders have assumed that all of the incoming energy is captured in the resulting black hole. we incorporate the inelasticity inherent in such processes and determine the prospects for discovering black holes in colliders and cosmic ray experiments, employing a dynamical model of hawking evolution. at the large hadron collider, inelasticity reduces rates by factors of 10 ^ 3 to 10 ^ 6 in the accessible parameter space, moderating, but not eliminating, hopes for black hole discovery. at the pierre auger observatory, rates are suppressed by a factor of 10. we evaluate the impact of cosmic ray observations on collider prospects.
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arxiv:hep-ph/0311365
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the potential barrier height at the interface formed by a metal contact and multiple one - dimensional ( 1d ) quasi - ballistic channels in field - effect transistors ( fets ) is evaluated across different carbon nanotube and nanowire device technologies by means of a landauer - b \ " uttiker - based extraction methodology ( lbm ) adapted for multiple 1d - channels. the extraction methodology yields values for an effective schottky barrier height and a gate coupling coefficient, an indicator of the device working at the quantum capacitance limit. the novel lbm - based approach embracing the mechanisms in 1d electronics is compared to the conventional activation energy method not considering such effects. the latter approach underestimates the potential barrier height at metal - channel interfaces in comparison to the novel methodology. a test structure based on a displaced gate device is proposed based on numerical device simulation results towards an improved accuracy of the method.
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arxiv:2207.04760
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this paper addresses the problem of matching $ n $ weighted graphs referring to an identical object or category. more specifically, matching the common node correspondences among graphs. this multi - graph matching problem involves two ingredients affecting the overall accuracy : i ) the local pairwise matching affinity score among graphs ; ii ) the global matching consistency that measures the uniqueness of the pairwise matching results by different chaining orders. previous studies typically either enforce the matching consistency constraints in the beginning of iterative optimization, which may propagate matching error both over iterations and across graph pairs ; or separate affinity optimizing and consistency regularization in two steps. this paper is motivated by the observation that matching consistency can serve as a regularizer in the affinity objective function when the function is biased due to noises or inappropriate modeling. we propose multi - graph matching methods to incorporate the two aspects by boosting the affinity score, meanwhile gradually infusing the consistency as a regularizer. furthermore, we propose a node - wise consistency / affinity - driven mechanism to elicit the common inlier nodes out of the irrelevant outliers. extensive results on both synthetic and public image datasets demonstrate the competency of the proposed algorithms.
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arxiv:1502.05840
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a proxy signature scheme allows a proxy signer to sign messages on behalf of an original signer. proxy signature schemes have found numerous practical applications such as grid computing, mobile agent systems and cloud applications. recently, jiang et al. proposed the first lattice - based proxy signature scheme and claimed that their scheme provides all the security properties of a secure proxy signature scheme. however, in this paper, we disprove their claim and show that an original signer is able to forge a proxy signature on any message.
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arxiv:1110.4196
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we report the first x - ray and radio polarimetric results of the neutron star ( ns ) low - mass x - ray binary ( lmxb ) atoll - source 4u 1728 - 34 using the imaging x - ray polarimetry explorer ( ixpe ) and australia telescope compact array ( atca ). we discovered that the x - ray source was polarized at pd = 1. 9 + / - 1. 0 % ( 3 - sigma errors ) with a polarization angle of pa = - 41 + / - 16 degree ( 3 - sigma errors ). simultaneous neutron star interior composition explorer ( nicer ) observations show that the source was in a relatively hard state, marking it as the first ixpe observation of an ns atoll source in the hard state. we do not detect any significant linear polarization ( lp ) in the radio band, with a 3 - sigma upper limit of 2 % at 5. 5 ghz and 1. 8 % at 9 ghz. combining the radio datasets provides the deepest upper limits on the radio polarization at < 1. 5 % on the linear and circular polarization ( measured at 7. 25 ghz ). the x - ray polarimetric results suggest a source geometry with a comptonization component possibly attributed to a boundary layer ( bl ) emission reflected off the disk, consistent with the other ns atoll sources.
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arxiv:2504.14021
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recent research has shown that syndrome - based belief propagation using layered scheduling ( slbp ) can not only accelerate the convergence rate but also improve the error rate performance by breaking the quantum trapping sets for quantum low - density parity - check ( qldpc ) codes, showcasing a result distinct from classical error correction codes. in this paper, we consider edge - wise informed dynamic scheduling ( ids ) for qldpc codes based on syndrome - based residual belief propagation ( srbp ). however, the construction of qldpc codes and the identical prior intrinsic information assignment will result in an equal residual in many edges, causing a performance limitation for srbp. two strategies, including edge pool design and error pre - correction, are introduced to tackle this obstacle and quantum trapping sets. then, a novel srbp equipped with a predict - and - reduce - error mechanism ( pre - srbp ) is proposed, which can provide a performance gain on considered qldpc codes of over one order of magnitude compared to slbp.
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arxiv:2410.01197
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two - dimensional ( 2d ) group - iii - v honeycomb films have attracted significant interest for their potential application in fields of quantum computing and nanoeletronics. searching for 2d iii - v films with high structural stability and large - gap are crucial for the realizations of dissipationless transport edge states using quantum spin hall ( qsh ) effect. based on first - principles calculations, we predict that the methyl - functionalized inbi monolayer ( inbich3 ) has no dynamic instability, and host a qsh state with a band gap as large as 0. 29 ev, exhibiting an interesting electronic behavior viable for room - temperature applications. the topological characteristic is confirmed by s - pxy bands inversion, topological invariant z2 number, and the time - reversal symmetry protected helical edge states. noticeably, the qsh states are tunable and robust against the mechanical strain, electric field and different levels of methyl coverages. we also find that inbich3 supported on h - bn substrate maintains a nontrivial qsh state, which harbors the edge states lying within the band gap of substrate. these findings demonstrate that the methyl - functionalized iii - v films may be a good qsh platform for device design and fabrication in spintronics.
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arxiv:1602.03959
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real - time emotion recognition ( rter ) in conversations is significant for developing emotionally intelligent chatting machines. without the future context in rter, it becomes critical to build the memory bank carefully for capturing historical context and summarize the memories appropriately to retrieve relevant information. we propose an attention gated hierarchical memory network ( aghmn ) to address the problems of prior work : ( 1 ) commonly used convolutional neural networks ( cnns ) for utterance feature extraction are less compatible in the memory modules ; ( 2 ) unidirectional gated recurrent units ( grus ) only allow each historical utterance to have context before it, preventing information propagation in the opposite direction ; ( 3 ) the soft attention for summarizing loses the positional and ordering information of memories, regardless of how the memory bank is built. particularly, we propose a hierarchical memory network ( hmn ) with a bidirectional gru ( bigru ) as the utterance reader and a bigru fusion layer for the interaction between historical utterances. for memory summarizing, we propose an attention gru ( agru ) where we utilize the attention weights to update the internal state of gru. we further promote the agru to a bidirectional variant ( biagru ) to balance the contextual information from recent memories and that from distant memories. we conduct experiments on two emotion conversation datasets with extensive analysis, demonstrating the efficacy of our aghmn models.
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arxiv:1911.09075
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we develop a model to describe the properties of random assemblies of polydisperse hard spheres. we show that the key features to describe the system are ( i ) the dependence between the free volume of a sphere and the various coordination numbers between the species, and ( ii ) the dependence of the coordination numbers with the concentration of species ; quantities that are calculated analytically. the model predicts the density of random close packing and random loose packing of polydisperse systems for a given distribution of ball size and describes packings for any interparticle friction coefficient. the formalism allows to determine the optimal packing over different distributions and may help to treat packing problems of non - spherical particles which are notoriously difficult to solve.
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arxiv:1006.1115
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in this paper we investigate the acceleration of the expansion of premixed spherical flames and evolution of the cellular patterns on their surfaces. an asymptotic model is used for the simulations and a spectral numerical algorithm is employed to study flames over large time intervals. numerous numerical experiments indicate that for large enough time intervals the acceleration of two - dimensional expanding flame ceases and the expansion rate stabilizes to a value significantly exceeding the burning rate. the importance of the effect of forcing was also confirmed and the validity of sectorial simulations of closed flames was studied in order to justify prospective use of the fourier spectral model for the three - dimensional spherical flames.
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arxiv:physics/0505102
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we introduce a new family of real simple modules over the quantum affine algebras, called the affine determinantial modules, which contains the kirillov - reshetikhin ( kr ) - modules as a special subfamily, and then prove t - systems among them which generalize the t - systems among kr - modules and unipotent quantum minors in the quantum unipotent coordinate algebras simultaneously. we develop new combinatorial tools : admissible chains of i - boxes which produce commuting families of affine determinantial modules, and box moves which describe the t - system in a combinatorial way. using these results, we prove that various module categories over the quantum affine algebras provide monoidal categorifications of cluster algebras. as special cases, hernandez - leclerc categories provide monoidal categorifications of the cluster algebras for an arbitrary quantum affine algebra.
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arxiv:2103.10067
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random tensors can be used to produce random matrices. this idea is, for instance, very natural when one studies random quantum states with the aim of exploring properties that are generically true, or true with some probability. we hereby study the moments generating function, in the sense of the stieltjes transform - i. e. the resolvent -, of a random matrix defined as a product of two different marginals of the same random tensor. we study the resolvent in two different asymptotical regimes. in the first regime, the resolvent is easily computed thanks to freeness results for the two different marginals and straightforward application of free harmonic analysis. in the second regime, we show that the resolvent satisfies an algebraic equation of degree six. this algebraic equation possesses roots whose expressions can be given explicitly in terms of radicals. we obtain this result by using an enumerative combinatorics approach. one of the interesting aspects of the second regime is that the corresponding probability density function interpolates between the square of a marchenko - pastur and the free multiplicative square of a marchenko - pastur law.
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arxiv:1907.08348
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within the framework of the theory of irreducible tensor operators, using well - known general analytical results for double sums ( $ \ sum _ { jm } $ ) of products of two $ 3j $ - wigner symbols, analytical expressions for single sums ( $ \ sum _ m $ ) for the values $ j _ 1 = j _ 2 = 1 $ and $ j = 2 $ parameters of the upper row $ 3j $ - wigner symbol are specified. the expressions obtained supplement the well - known analytical results of the theory of angular momentum and are in demand in solving, in particular, such problems of atomic physics as the construction of a nonrelativistic quantum theory of single and double bremsstrahlung when a photon is scattered by an atom ( atomic ion ) ( hopersky et al [ 6, 7, 8 ] ) and two - photon resonance single ionization of the deep shell of an atomic ion ( hopersky et al [ 9 ] ).
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arxiv:2504.11567
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this letter explores an implementation of a novel thin film 1 - by - 4 reconfigurable intelligent surface ( ris ) designed for future communication and sensing scenarios. utilizing cost - effective inkjet printing methods and additive manufacturing, our approach significantly simplifies the ris construction process and reduces production costs. the ris, fabricated on a flexible and lightweight polyethylene terephthalate ( pet ) substrate, integrates antennas, switching circuitry, and a microcontroller unit ( mcu ), without a ground shield. this setup enables individual and simultaneous control of each ris element, manipulating the captured carrier signal by reflecting and refracting its dominant harmonics. beams of the harmonics can be steered to multiple desired directions at both front and back sides of the surface. measurement results of the beam steering show that the ris has the potential to enable ris - aided communication and sensing applications.
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arxiv:2406.06343
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we develop new algorithms for estimating heterogeneous treatment effects, combining recent developments in transfer learning for neural networks with insights from the causal inference literature. by taking advantage of transfer learning, we are able to efficiently use different data sources that are related to the same underlying causal mechanisms. we compare our algorithms with those in the extant literature using extensive simulation studies based on large - scale voter persuasion experiments and the mnist database. our methods can perform an order of magnitude better than existing benchmarks while using a fraction of the data.
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arxiv:1808.07804
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we propose a means of omni - directional contact detection using accelerometers instead of tactile sensors for object shape estimation using touch. unlike tactile sensors, our contact - based detection method tends to induce a degree of uncertainty with false - positive contact data because the sensors may react not only to actual contact but also to the unstable behavior of the robot. therefore, it is crucial to consider a robust shape estimation method capable of handling such false - positive contact data. to realize this, we introduce the concept of heteroscedasticity into the contact data and propose a robust shape estimation algorithm based on gaussian process implicit surfaces ( gpis ). we confirmed that our algorithm not only reduces shape estimation errors caused by false - positive contact data but also distinguishes false - positive contact data more clearly than the gpis through simulations and actual experiments using a quadcopter.
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arxiv:2104.10318
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the concept of generalised ( in the sense of colombeau ) connection on a principal fibre bundle is introduced. this definition is then used to extend results concerning the geometry of principal fibre bundles to those that only have a generalised connection. some applications to singular solutions of yang - mills theory are given.
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arxiv:math/0403040
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a lattice diagram is a finite list l = ( ( p _ 1, q _ 1 ),..., ( p _ n, q _ n ) of lattice cells. the corresponding lattice diagram determinant is \ delta _ l ( x ; y ) = \ det \ | x _ i ^ { p _ j } y _ i ^ { q _ j } \ |. these lattice diagram determinants are crucial in the study of the so - called ` ` n! conjecture ' ' of a. garsia and m. haiman. the space m _ l is the space spanned by all partial derivatives of \ delta _ l ( x ; y ). the ` ` shift operators ' ', which are particular partial symmetric derivative operators are very useful in the comprehension of the structure of the m _ l spaces. we describe here how a schur function partial derivative operator acts on lattice diagrams with distinct cells in the positive quadrant.
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arxiv:math/0111246
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we study the interaction of views, queries, and background knowledge in the form of existential rules. the motivating questions concern monotonic determinacy of a query using views w. r. t. rules, which refers to the ability to recover the query answer from the views via a monotone function. we study the decidability of monotonic determinacy, and compare with variations that require the ` ` recovery function ' ' to be in a well - known monotone query language, such as conjunctive queries or datalog. surprisingly, we find that even in the presence of basic existential rules, the borderline between well - behaved and badly - behaved answerability differs radically from the unconstrained case. in order to understand this boundary, we require new results concerning entailment problems involving views and rules.
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arxiv:2407.14907
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the subnet neural network architecture has been developed to identify nonlinear state - space models from input - output data. to achieve this, it combines the rolled - out nonlinear state - space equations and a state encoder function, both parameterised as neural networks the encoder function is introduced to reconstruct the current state from past input - output data. hence, it enables the forward simulation of the rolled - out state - space model. while this approach has shown to provide high - accuracy and consistent model estimation, its convergence can be significantly improved by efficient initialization of the training process. this paper focuses on such an initialisation of the subspace encoder approach using the best linear approximation ( bla ). using the bla provided state - space matrices and its associated reconstructability map, both the state - transition part of the network and the encoder are initialized. the performance of the improved initialisation scheme is evaluated on a wiener - hammerstein simulation example and a benchmark dataset. the results show that for a weakly nonlinear system, the proposed initialisation based on the linear reconstructability map results in a faster convergence and a better model quality.
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arxiv:2304.02119
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we present a new method of deriving shapes of entanglement wedges directly from cft calculations. we point out that a reduced density matrix in holographic cfts possesses a sharp wedge structure such that inside the wedge we can distinguish two local excitations, while outside we cannot. we can determine this wedge, which we call a cft wedge, by computing a distinguishability measure. we find that cft wedges defined by the fidelity or bures distance as a distinguishability measure, coincide perfectly with shadows of entanglement wedges in ads / cft. we confirm this agreement between cft wedges and entanglement wedges for two dimensional holographic cfts where the subsystem is chosen to be an interval or double intervals, as well as higher dimensional cfts with a round ball subsystem. on the other hand if we consider a free scalar cft, we find that there are no sharp cft wedges. this shows that sharp entanglement wedges emerge only for holographic cfts owing to the large n factorization. we also generalize our analysis to a time - dependent example and to a holographic boundary conformal field theory ( ads / bcft ). finally we study other distinguishability measures to define cft wedges. we observe that some of measures lead to cft wedges which slightly deviate from the entanglement wedges in ads / cft and we give a heuristic explanation for this. this paper is an extended version of our earlier letter arxiv : 1908. 09939 and includes various new observations and examples.
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arxiv:1912.08423
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we theoretically investigate first and second sound modes of a unitary fermi gas trapped in a highly oblate harmonic trap at finite temperatures. following the idea by stringari and co - workers { [ } phys. rev. lett. \ textbf { 105 }, 150402 ( 2010 ) { ] }, we argue that these modes can be described by the simplified two - dimensional two - fluid hydrodynamic equations. two possible schemes - sound wave propagation and breathing mode excitation - are considered. we calculate the sound wave velocities and discretized sound mode frequencies, as a function of temperature. we find that in both schemes, the coupling between first and second sound modes is large enough to induce significant density fluctuations, suggesting that second sound can be directly observed by measuring \ textit { in - situ } density profiles. the frequency of the second sound breathing mode is found to be highly sensitive to the superfluid density.
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arxiv:1410.1340
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in a recent paper, we presented the ku leuven audiovisual, gaze - controlled auditory attention decoding ( av - gc - aad ) dataset, in which we recorded electroencephalography ( eeg ) signals of participants attending to one out of two competing speakers under various audiovisual conditions. the main goal of this dataset was to disentangle the direction of gaze from the direction of auditory attention, in order to reveal gaze - related shortcuts in existing spatial aad algorithms that aim to decode the ( direction of ) auditory attention directly from the eeg. various methods based on spatial aad do not achieve significant above - chance performances on our av - gc - aad dataset, indicating that previously reported results were mainly driven by eye gaze confounds in existing datasets. still, these adverse outcomes are often discarded for reasons that are attributed to the limitations of the av - gc - aad dataset, such as the limited amount of data to train a working model, too much data heterogeneity due to different audiovisual conditions, or participants allegedly being unable to focus their auditory attention under the complex instructions. in this paper, we present the results of the linear stimulus reconstruction aad algorithm and show that high aad accuracy can be obtained within each individual condition and that the model generalizes across conditions, across new subjects, and even across datasets. therefore, we eliminate any doubts that the inadequacy of the av - gc - aad dataset is the primary reason for the ( spatial ) aad algorithms failing to achieve above - chance performance when compared to other datasets. furthermore, this report provides a simple baseline evaluation procedure ( including source code ) that can serve as the minimal benchmark for all future aad algorithms evaluated on this dataset.
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arxiv:2412.01401
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despite the fact that quantum gravity theory still remains elusive, it is generally expected that it will bring the picture of a space - time foam at short distances leading to lorenz invariance violation ( liv ) manifested e. g. by energy dependent modification of standard relativistic dispersion relation. one direction of research, pursued intensively is to measure energy dependent time of arrival delays in photons emitted by astrophysical sources located at cosmological distances. this is tempered however by our ignorance of either intrinsic delay ( at source frame ) in different energy channels or as recently shown, the correct model of the background cosmology. in this paper we propose a new test based on gravitational lensing. monitoring time delays between images performed in different energy channels ( e. g. optical - low energy and tev photons ) may reveal extra delays due to distorted dispersion relation typical in liv theories - a test which is free from the systematics inherent in other settings.
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arxiv:0712.0941
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we propose a phenomenological theory for topological crystalline insulators with time reversal and $ c _ 4 $ symmetries. first, we introduce a fictitious space and transformation of electromagnetic field operators. this transformation leaves the speed of light unchanged but changes the elementary charge to $ \ sqrt { 2 } e $. then we formulate the theory of topological crystalline insulators in terms of transformed fields in this fictitious space as 3d bf theory containing $ \ pi $ - flux excitations. it is known that a 3d bf theory with half flux quantum excitations describes low energy properties of time reversal invariant insulators. by making an inverse transform we recover the effective field theory in original space. it turns out that this field theory contains quarter flux quantum excitations.
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arxiv:1205.3560
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we investigate the projected minimum constraints set by next - generation gravitational wave detectors einstein telescope and lisa on the abundance of primordial black holes relative to dark matter from both resolvable mergers and the stochastic gravitational wave background ( sgwb ) for extended primordial black hole mass distributions. we consider broad power law distributions for a range of negative and positive exponents $ \ gamma $ and top - hat distributions ( with $ \ gamma = 0 $ ) and use the imrphenomxas waveforms to simulate binary sources up to mass ratios $ q _ \ mathrm { max } = 1000 $ and redshifts $ z = 300 $. our results suggest that accounting for extended mass distributions have the most apparent impact when considering mergers at high redshifts $ z > 30 $, for which the constraint curves have broader mass windows and shift to higher abundances compared to when a monochromatic distribution is assumed ; on the other hand, constraints from low - redshift mergers and the sgwb do not change much with the assumed mass distribution. at high redshifts, astrophysical black holes are not expected to contribute significantly, providing possible smoking - gun evidence for pbhs. constraints derived from lisa and et observations would complement each other by probing different pbh mass windows and this holds for the extended mass distributions studied.
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arxiv:2406.12281
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we show that a class of torsional compactifications of the heterotic string are dual to conventional kahler heterotic string compactifications. this observation follows from the recently proposed analogue of the c - map for the heterotic string.
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arxiv:0707.0295
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banks ' performance is an important topic for both professionals and researchers. given the important literature on this subject, this paper aims to bring an up - to - date and organized review of literature on the determinants of banks performance. this paper discusses the main approaches that molded the debate on banks performance and their main determinants. an in - depth understanding of these latter may allow on the one hand, bank managers and regulators to improve the sector efficiency and to deal with the new trends shaping the future of their industry and on the other hand, academicians to enrich research and knowledge on this field. through the analysis of 54 studies published in 42 peer - reviewed journals, we show that despite the importance of the existent literature, the subject of bank performance factors did not reveal all its secrets and still constitute a fertile field for critical debates, especially since the covid - 19 and the increasingly pressing rise in power of digital transformation and artificial intelligence in general and fintechs in particular. the study concludes by suggesting new promising research avenues.
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arxiv:2311.08617
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this paper concerns the propagation of high frequency wave - beams in highly turbulent atmospheres. using a paraxial model of wave propagation, we show in the long - distance weak - coupling regime that the wavefields are approximately described by a complex gaussian field whose scintillation index is unity. this provides a model of the speckle formation observed in many practical settings. the main step of the derivation consists in showing that closed - form moment equations in the it \ ^ o - schr \ " odinger regime are still approximately satisfied in the paraxial regime. the rest of the proof is then an extension of results derived in [ bal, g. and nair, a., arxiv : 2402. 17107. ]
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arxiv:2409.09514
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this paper contributes to the verification of programs written in bitcoin ' s smart contract language script in the interactive theorem prover agda. it focuses on the security property of access control for script programs that govern the distribution of bitcoins. it advocates that weakest preconditions in the context of hoare triples are the appropriate notion for verifying access control. it aims at obtaining human - readable descriptions of weakest preconditions in order to close the validation gap between user requirements and formal specification of smart contracts. as examples for the proposed approach, the paper focuses on two standard script programs that govern the distribution of bitcoins, pay to public key hash ( p2pkh ) and pay to multisig ( p2ms ). the paper introduces an operational semantics of the script commands used in p2pkh and p2ms, which is formalised in the agda proof assistant and reasoned about using hoare triples. two methodologies for obtaining human - readable descriptions of weakest preconditions are discussed : ( 1 ) a step - by - step approach, which works backwards instruction by instruction through a script, sometimes grouping several instructions together ; ( 2 ) symbolic execution of the code and translation into a nested case distinction, which allows to read off weakest preconditions as the disjunction of conjunctions of conditions along accepting paths. a syntax for equational reasoning with hoare triples is defined in order to formalise those approaches in agda. keywords and phrases : blockchain ; cryptocurrency ; bitcoin ; agda ; verification ; hoare logic ; bitcoin script ; p2pkh ; p2ms ; access control ; weakest precondition ; predicate transformer semantics ; provable correctness ; symbolic execution ; smart contracts
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arxiv:2203.03054
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emissions of free neutrons and protons from the central collisions of 124sn + 124sn and 112sn + 112sn reactions are simulated using the improved quantum molecular dynamics model with two different density dependence of the symmetry energy in the nuclear equation of state. the constructed double ratios of the neutron to proton ratios of the two reaction systems are found to be sensitive to the symmetry terms in the eos. the effect of cluster formation is examined and found to affect the double ratios mainly in the low energy region. in order to extract better information on symmetry energy with transport models, it is therefore important to have accurate data in the high energy region which also is affected minimally by sequential decays.
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arxiv:0708.3684
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we present a quantitative and fully non - perturbative description of the ergodic phase of quantum chaos in the setting of two - dimensional gravity. to this end we describe the doubly non - perturbative completion of semiclassical 2d gravity in terms of its associated universe field theory. the guiding principle of our analysis is a flavor - matrix theory ( fmt ) description of the ergodic phase of holographic gravity, which exhibits $ \ mathrm { u } ( n | n ) $ causal symmetry breaking and restoration. jt gravity and its 2d - gravity cousins alone do not realize an action principle with causal symmetry, however we demonstrate that their { \ it universe field theory }, the kodaira - spencer ( ks ) theory of gravity, does. after directly deriving the fmt from brane - antibrane correlators in ks theory, we show that causal symmetry breaking and restoration can be understood geometrically in terms of different ( topological ) d - brane vacua. we interpret our results in terms of an open - closed string duality between holomorphic chern - simons theory and its closed - string equivalent, the ks theory of gravity. emphasis will be put on relating these geometric principles to the characteristic spectral correlations of the quantum ergodic phase.
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arxiv:2204.07583
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regression methods for interval - valued data have been increasingly studied in recent years. as most of the existing works focus on linear models, it is important to note that many problems in practice are nonlinear in nature and therefore development of nonlinear regression tools for interval - valued data is crucial. in this paper, we propose a tree - based regression method for interval - valued data, which is well applicable to both linear and nonlinear problems. unlike linear regression models that usually require additional constraints to ensure positivity of the predicted interval length, the proposed method estimates the regression function in a nonparametric way, so the predicted length is naturally positive without any constraints. a simulation study is conducted that compares our method to popular existing regression models for interval - valued data under both linear and nonlinear settings. furthermore, a real data example is presented where we apply our method to analyze price range data of the dow jones industrial average index and its component stocks.
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arxiv:2201.02948
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we propose a way of including the next - to - leading ( nlo ) order spin - spin coupling into an effective - one - body ( eob ) hamiltonian. this work extends [ s. balmelli and p. jetzer, phys. rev. d 87, 124036 ( 2013 ) ], which is restricted to the case of equatorial orbits and aligned spins, to general orbits with arbitrary spin orientations. this is done applying appropriate canonical phase - space transformations to the nlo spin - spin hamiltonian in arnowitt - deser - misner ( adm ) coordinates, and systematically adding " effectiv " quantities at nlo to all spin - squared terms appearing in the eob hamiltonian. as required by consistency, the introduced quantities reduce to zero in the test - mass limit. we expose the result both in a general gauge and in a gauge - fixed form. the last is chosen such as to minimize the number of new coefficients that have to be inserted into the effective spin squared. as a result, the 25 parameters that describe the adm nlo spin - spin dynamics get condensed into only 12 eob terms.
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arxiv:1502.01343
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smart home assistants function best when user commands are direct and well - specified ( e. g., " turn on the kitchen light " ), or when a hard - coded routine specifies the response. in more natural communication, however, human speech is unconstrained, often describing goals ( e. g., " make it cozy in here " or " help me save energy " ) rather than indicating specific target devices and actions to take on those devices. current systems fail to understand these under - specified commands since they cannot reason about devices and settings as they relate to human situations. we introduce large language models ( llms ) to this problem space, exploring their use for controlling devices and creating automation routines in response to under - specified user commands in smart homes. we empirically study the baseline quality and failure modes of llm - created action plans with a survey of age - diverse users. we find that llms can reason creatively to achieve challenging goals, but they experience patterns of failure that diminish their usefulness. we address these gaps with sasha, a smarter smart home assistant. sasha responds to loosely - constrained commands like " make it cozy " or " help me sleep better " by executing plans to achieve user goals, e. g., setting a mood with available devices, or devising automation routines. we implement and evaluate sasha in a hands - on user study, showing the capabilities and limitations of llm - driven smart homes when faced with unconstrained user - generated scenarios.
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arxiv:2305.09802
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part 2 of this monograph builds on the introduction to tensor networks and their operations presented in part 1. it focuses on tensor network models for super - compressed higher - order representation of data / parameters and related cost functions, while providing an outline of their applications in machine learning and data analytics. a particular emphasis is on the tensor train ( tt ) and hierarchical tucker ( ht ) decompositions, and their physically meaningful interpretations which reflect the scalability of the tensor network approach. through a graphical approach, we also elucidate how, by virtue of the underlying low - rank tensor approximations and sophisticated contractions of core tensors, tensor networks have the ability to perform distributed computations on otherwise prohibitively large volumes of data / parameters, thereby alleviating or even eliminating the curse of dimensionality. the usefulness of this concept is illustrated over a number of applied areas, including generalized regression and classification ( support tensor machines, canonical correlation analysis, higher order partial least squares ), generalized eigenvalue decomposition, riemannian optimization, and in the optimization of deep neural networks. part 1 and part 2 of this work can be used either as stand - alone separate texts, or indeed as a conjoint comprehensive review of the exciting field of low - rank tensor networks and tensor decompositions.
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arxiv:1708.09165
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we consider the ground state of vortices in a rotating bose - einstein condensate that is loaded in a corotating two - dimensional optical lattice. due to the competition between vortex interactions and their potential energy, the vortices arrange themselves in various patterns, depending on the strength of the optical potential and the vortex density. we outline a method to determine the phase diagram for arbitrary vortex filling factor. using this method, we discuss several filling factors explicitly. for increasing strength of the optical lattice, the system exhibits a transition from the unpinned hexagonal lattice to a lattice structure where all the vortices are pinned by the optical lattice. the geometry of this fully pinned vortex lattice depends on the filling factor and is either square or triangular. for some filling factors there is an intermediate half - pinned phase where only half of the vortices is pinned. we also consider the case of a two - component bose - einstein condensate, where the possible coexistence of the above - mentioned phases further enriches the phase diagram. in addition, we calculate the dispersion of the low - lying collective modes of the vortex lattice and find that, depending on the structure of the ground state, they can be gapped or gapless. moreover, in the half - pinned and fully pinned phases, the collective mode dispersion is anisotropic. possible experiments to probe the collective mode spectrum, and in particular the gap, are suggested.
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arxiv:cond-mat/0411307
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one - shot nas method has attracted much interest from the research community due to its remarkable training efficiency and capacity to discover high performance models. however, the search spaces of previous one - shot based works usually relied on hand - craft design and were short for flexibility on the network topology. in this work, we try to enhance the one - shot nas by exploring high - performing network architectures in our large - scale topology augmented search space ( i. e., over 3. 4 * 10 ^ 10 different topological structures ). specifically, the difficulties for architecture searching in such a complex space has been eliminated by the proposed stabilized share - parameter proxy, which employs stochastic gradient langevin dynamics to enable fast shared parameter sampling, so as to achieve stabilized measurement of architecture performance even in search space with complex topological structures. the proposed method, namely stablized topological neural architecture search ( st - nas ), achieves state - of - the - art performance under multiply - adds ( madds ) constraint on imagenet. our lite model st - nas - a achieves 76. 4 % top - 1 accuracy with only 326m madds. our moderate model st - nas - b achieves 77. 9 % top - 1 accuracy just required 503m madds. both of our models offer superior performances in comparison to other concurrent works on one - shot nas.
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arxiv:2005.10511
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we present an analysis of a partially directed walk model of a polymer which at one end is tethered to a sticky surface and at the other end is subjected to a pulling force at fixed angle away from the point of tethering. using the kernel method, we derive the full generating function for this model in two and three dimensions and obtain the respective phase diagrams. we observe adsorbed and desorbed phases with a thermodynamic phase transition in between. in the absence of a pulling force this model has a second - order thermal desorption transition which merely gets shifted by the presence of a lateral pulling force. on the other hand, if the pulling force contains a non - zero vertical component this transition becomes first - order. strikingly, we find that if the angle between the pulling force and the surface is beneath a critical value, a sufficiently strong force will induce polymer adsorption, no matter how large the temperature of the system. our findings are similar in two and three dimensions, an additional feature in three dimensions being the occurrence of a reentrance transition at constant pulling force for small temperature, which has been observed previously for this model in the presence of pure vertical pulling. interestingly, the reentrance phenomenon vanishes under certain pulling angles, with details depending on how the three - dimensional polymer is modeled.
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arxiv:1007.3160
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the $ \ alpha $ - $ t _ 3 $ system undergoes a topological phase transition ( tpt ) between two distinct quantum spin - hall phases across $ \ alpha = 0. 5 $ when the spin - orbit interaction of kane - mele type is taken into consideration. as a hallmark of such a tpt, we find that the berry curvature and the orbital magnetic moment change their respective signs across the tpt. we also find the trails of the tpt in another physical observable, namely, the orbital magnetization ( om ) that can be, in principle, detected experimentally through the circular dichroism associated with optical absorption. the topological features of the om are understood in terms of valley and spin physics. the valley - resolved om ( vrom ) and the spin - resolved om ( srom ) exhibit interesting characteristics related to the valley and the spin chern number when the chemical potential is tuned in the forbidden gap ( s ) of the energy spectrum. in particular, we find that the slope of the vrom versus the chemical potential in the forbidden gap changes its sign abruptly across the tpt, which is also consistent with the corresponding change in the valley chern number. moreover, the slope of the srom demonstrates a sudden jump by one unit of $ e / h $ ( where $ e $ is the electronic charge and $ h $ is the planck ' s constant ) across the tpt, which is also in agreement with the corresponding change in the spin chern number. it is further seen that a definite spin - valley optical selection rule governs the circular dichroism. the $ k $ - resolved degree of the optical polarization and the low - frequency differential optical absorbance manifest sign change across the tpt. we discuss experimentally viable signatures of different quantum spin - hall phases in the optical absorbance.
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arxiv:2309.07074
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we establish the rationality of the stable conjugation - invariant word norm on free groups and virtually free coxeter groups.
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arxiv:2304.03618
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adiabatic shuttling of single impurity bound electrons to gate induced surface states in semiconductors has attracted much attention in recent times, mostly in the context of solid - state quantum computer architecture. a recent transport spectroscopy experiment for the first time was able to probe the stark shifted spectrum of a single donor in silicon buried close to a gate. here we present the full theoretical model involving large - scale quantum mechanical simulations that was used to compute the stark shifted donor states in order to interpret the experimental data. use of atomistic tight - binding technique on a domain of over a million atoms helped not only to incorporate the full band structure of the host, but also to treat realistic device geometries and donor models, and to use a large enough basis set to capture any number of donor states. the method yields a quantitative description of the symmetry transition that the donor electron undergoes from a 3d coulomb confined state to a 2d surface state as the electric field is ramped up adiabatically. in the intermediate field regime, the electron resides in a superposition between the states of the atomic donor potential and that of the quantum dot like states at the surface. in addition to determining the effect of field and donor depth on the electronic structure, the model also provides a basis to distinguish between a phosphorus and an arsenic donor based on their stark signature. the method also captures valley - orbit splitting in both the donor well and the interface well, a quantity critical to silicon qubits. the work concludes with a detailed analysis of the effects of screening on the donor spectrum.
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arxiv:0904.4281
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cyclization of dna with sticky ends is commonly used to construct dna minicircles and to measure dna bendability. the cyclization probability of short dna ( < 150 bp ) has a strong length dependence, but how it depends on the rotational positioning of the sticky ends around the helical axis is less clear. to shed light upon the determinants of the cyclization probability of short dna, we measured cyclization and decyclization rates of ~ 100 - bp dna with sticky ends over two helical periods using single - molecule fluorescence resonance energy transfer ( fret ). the cyclization rate increases monotonically with length, indicating no excess twisting, while the decyclization rate oscillates with length, higher at half - integer helical turns and lower at integer helical turns. the oscillation profile is kinetically and thermodynamically consistent with a three - state cyclization model in which sticky - ended short dna first bends into a torsionally - relaxed teardrop, and subsequently transitions to a more stable loop upon terminal base stacking. we also show that the looping probability density ( the j factor ) extracted from this study is in good agreement with the worm - like chain model near 100 bp. for shorter dna, we discuss various experimental factors that prevent an accurate measurement of the j factor.
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arxiv:1812.09352
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we demonstrate the applicability of the $ \ epsilon $ - convergence algorithm in extracting the critical temperatures and critical exponents of three - dimensional ising models. we analyze the low temperature magnetization as well as high temperature susceptibility series of simple cubic, body - centered cubic, face - centered cubic and diamond lattices, using two different variables for the inverse critical temperature. in the case of simple cubic lattices, the magnetization series was modified to deduce accurate values of the critical temperatures. the alternate variable for dimensionless inverse temperature suggested by guttmann and thompson has also been employed for the estimation of the critical parameters.
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arxiv:2410.15785
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stars orbiting within 1 $ \ arcsec $ of the supermassive black hole in the galactic centre, sgr a *, are notoriously difficult to detect due to obscuration by gas and dust. we show that some stars orbiting this region may be detectable via synchrotron emission. in such instances, a bow shock forms around the star and accelerates the electrons. we calculate that around the 10 ghz band ( radio ) and at 10 $ ^ { 14 } $ hz ( infrared ) the luminosity of a star orbiting the black hole is comparable to the luminosity of sgr a *. the strength of the synchrotron emission depends on a number of factors including the star ' s orbital velocity. thus, the ideal time to observe the synchrotron flux is when the star is at pericenter. the star s2 will be $ \ sim 0. 015 \ arcsec $ from sgr a * in 2018, and is an excellent target to test our predictions.
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arxiv:1509.06251
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quantum machine learning ( qml ) has emerged as an innovative framework with the potential to uncover complex patterns by leveraging quantum systems ability to simulate and exploit high - dimensional latent spaces, particularly in learning tasks. quantum neural network ( qnn ) frameworks are inherently sensitive to the precision of gradient calculations and the computational limitations of current quantum hardware as unitary rotations introduce overhead from complex number computations, and the quantum gate operation speed remains a bottleneck for practical implementations. in this study, we introduce quantum parallel information exchange ( qpie ) hybrid network, a new non - sequential hybrid classical quantum model architecture, leveraging quantum transfer learning by feeding pre - trained parameters from classical neural networks into quantum circuits, which enables efficient pattern recognition and temporal series data prediction by utilizing non - clifford parameterized quantum gates thereby enhancing both learning efficiency and representational capacity. additionally, we develop a dynamic gradient selection method that applies the parameter shift rule on quantum processing units ( qpus ) and adjoint differentiation on gpus. our results demonstrate model performance exhibiting higher accuracy in ad - hoc benchmarks, lowering approximately 88 % convergence rate for extra stochasticity time - series data within 100 - steps, and showcasing a more unbaised eigenvalue spectrum of the fisher information matrix on cpu / gpu and ionq qpu simulators.
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arxiv:2504.04235
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channel and spatial attentions have respectively brought significant improvements in extracting feature dependencies and spatial structure relations for various downstream vision tasks. while their combination is more beneficial for leveraging their individual strengths, the synergy between channel and spatial attentions has not been fully explored, lacking in fully harness the synergistic potential of multi - semantic information for feature guidance and mitigation of semantic disparities. our study attempts to reveal the synergistic relationship between spatial and channel attention at multiple semantic levels, proposing a novel spatial and channel synergistic attention module ( scsa ). our scsa consists of two parts : the shareable multi - semantic spatial attention ( smsa ) and the progressive channel - wise self - attention ( pcsa ). smsa integrates multi - semantic information and utilizes a progressive compression strategy to inject discriminative spatial priors into pcsa ' s channel self - attention, effectively guiding channel recalibration. additionally, the robust feature interactions based on the self - attention mechanism in pcsa further mitigate the disparities in multi - semantic information among different sub - features within smsa. we conduct extensive experiments on seven benchmark datasets, including classification on imagenet - 1k, object detection on mscoco 2017, segmentation on ade20k, and four other complex scene detection datasets. our results demonstrate that our proposed scsa not only surpasses the current state - of - the - art attention but also exhibits enhanced generalization capabilities across various task scenarios. the code and models are available at : https : / / github. com / hzai - zjnu / scsa.
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arxiv:2407.05128
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for a smooth family of exact forms on a smooth manifold, an algorithm for computing a primitive family smoothly dependent on parameters is given. the algorithm is presented in the context of a diagram chasing argument in the \ v { c } ech - de rham complex. in addition, explicit formulas for such primitive family are presented.
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arxiv:1903.07830
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we consider closed quantum many - body systems subject to stochastic resetting. this means that their unitary time evolution is interrupted by resets at randomly selected times. when a reset takes place the system is reinitialized to a state chosen from a set of reset states conditionally on the outcome of a measurement taken immediately before resetting. we construct analytically the resulting non - equilibrium stationary state, thereby establishing an explicit connection between quantum quenches in closed systems and the emergent open system dynamics induced by stochastic resetting. we discuss as an application the paradigmatic transverse - field quantum ising chain. we show that signatures of its ground - state quantum phase transition are visible in the steady state of the reset dynamics as a sharp crossover. our findings show that a controlled stochastic resetting dynamics allows to design non - equilibrium stationary states of quantum many - body systems, where uncontrolled dissipation and heating can be prevented. these states can thus be created on demand and exploited, e. g., as a resource for quantum enhanced sensing on quantum simulator platforms.
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arxiv:2106.13761
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we consider the interactions of finite dipoles in a doubly - periodic domain. a finite dipole is a pair of equal and opposite strength point vortices separated by a finite distance. the dynamics of multiple finite dipoles in an unbounded inviscid uid was first proposed by tchieu, kanso & newton in [ 1 ] as a model that captures the " far - field " hydrodynamic interactions in fish schools. in this paper, we formulate the equations of motion governing the dynamics of finite - dipoles in a doubly - periodic domain. we show that a single dipole in a doubly - periodic domain exhibits periodic and aperiodic behavior, in contrast to a single dipole in an unbounded domain. in the case of two dipoles in doubly - periodic domain, we identify a number of interesting trajectories including collision, collision avoidance, and passive synchronization of the dipoles. we then examine two types of dipole lattices : rectangular and diamond. we verify that these lattices are in a state of relative equilibrium and show that the rectangular lattice is unstable while the diamond lattice is linearly stable for a range of perturbations. we conclude by commenting on the insights these models provide in the context of fish schooling.
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arxiv:1304.6795
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` ether - drift ' experiments have played a crucial role for the origin of relativity. though, a recent re - analysis shows that those original measurements where light was still propagating in gaseous systems, differently from the modern experiments in vacuum and in solid dielectrics, indicate a small universal anisotropy which is naturally interpreted in terms of a non - local thermal gradient. we argue that this could possibly be the effect, on weakly bound gaseous matter, of the temperature gradient due to the earth ' s motion within the cosmic background radiation ( cbr ). therefore, a check with modern laser interferometers is needed to reproduce the conditions of those early measurements with today ' s much greater accuracy. we emphasize that an unambiguous confirmation of our interpretation would have far reaching consequences. for instance, it would also imply that all physical systems on the moving earth are exposed to a tiny energy flow, an effect that, in principle, could induce forms of self - organization in matter.
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arxiv:1601.06518
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derivation of two - time second - order correlation function by following approaches such as stochastic differential equation, coherent - state propagator, and quasi - statistical distribution function is presented. in the process, the time dependence of the operators is transferred to the density operator by making use of trace operation in which the coherent state propagator and $ q $ - function that represent the quantum system under consideration are expressed in terms of different time parameters. even though the number of resulting integrations are found to be large, the accompanying implementation turns out to be straightforward in view that the associated $ c $ - number functions are gaussian by nature. in relation to the asserted possibility of rewriting the result of one of the approaches in terms of the other, the presented derivation is expected to lay a strong foundation for viable technique of calculating correlations of various moments at different times that can be deployed in revealing quantum correlations.
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arxiv:2406.10546
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we present an extension of the twistor - motivated mhv vertices and accompanying rules presented by cachazo, svrvcek and witten to the construction of vector - boson currents coupling to an arbitrary source. in particular, we give rules for constructing off - shell vector - boson currents with one fermion pair and n gluons of arbitrary helicity. these currents may be employed directly in the computation of electroweak amplitudes. the rules yield expressions in agreement with previously - obtained results for z, w, \ gamma ^ * - - > qbar q + n gluons ( analytically up to n = 3, beyond via the berends - - giele recursion relations ). we also confirm that the contribution to a seven - point amplitude containing the non - abelian triple vector - boson coupling obtained using the next - to - mhv currents matches the previous result in the literature.
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arxiv:hep-ph/0412167
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parallelograms are one of the basic building blocks in two - dimensional tiling. they have important applications in a wide variety of science and engineering fields, such as wireless communication networks, urban transportation, operations research, etc. different from rectangles and squares, the coordinates of a random point in parallelograms are no longer independent. as a case study of parallelograms, the explicit probability density functions of the random euclidean distances associated with rhombuses are given in this report, when both endpoints are randomly distributed in 1 ) the same rhombus, 2 ) two parallel rhombuses sharing a side, and 3 ) two rhombuses having a common diagonal, respectively. the accuracy of the distance distribution functions is verified by simulation, and the correctness is validated by a recursion and a probabilistic sum. the first two statistical moments of the random distances, and the polynomial fit of the density functions are also given in this report for practical uses.
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arxiv:1106.1257
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we propose a way to introduce the currents responsible for the chiral magnetic effect, and similar phenomena, into the ads / cft description. such currents are thought to occur in heavy ion collisions due to topologically non - trivial field configurations and in dense stars due to beta decay. they may be responsible for the p and cp odd effects seen at rhic and the anomalously large velocities observed in some pulsars. we discuss the boundary conditions that allow the phenomenon to exist in real systems and show how one would introduce similar boundary conditions into a holographic model of qcd such that the current is reproduced.
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arxiv:1009.4230
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we say that a finite group $ g $ satisfies the independence property if, for every pair of distinct elements $ x $ and $ y $ of $ g $, either $ \ { x, y \ } $ is contained in a minimal generating set for $ g $ or one of $ x $ and $ y $ is a power of the other. we give a complete classification of the finite groups with this property, and in particular prove that every such group is supersoluble. a key ingredient of our proof is a theorem showing that all but three finite almost simple groups $ h $ contain an element $ s $ such that the maximal subgroups of $ h $ containing $ s $, but not containing the socle of $ h $, are pairwise non - conjugate.
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arxiv:2208.04064
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in traditional neural network architectures, a multilayer perceptron ( mlp ) is typically employed as a classification block following the feature extraction stage. however, the kolmogorov - arnold network ( kan ) presents a promising alternative to mlp, offering the potential to enhance prediction accuracy. in this paper, we propose the replacement of linear and convolutional layers of traditional networks with kan - based counterparts. these modifications allowed us to significantly increase the per - pixel classification accuracy for hyperspectral remote - sensing images. we modified seven different neural network architectures for hyperspectral image classification and observed a substantial improvement in the classification accuracy across all the networks. the architectures considered in the paper include baseline mlp, state - of - the - art 1d ( 1dcnn ) and 3d convolutional ( two different 3dcnn, nm3dcnn ), and transformer ( ssftt ) architectures, as well as newly proposed m1dcnn. the greatest effect was achieved for convolutional networks working exclusively on spectral data, and the best classification quality was achieved using a kan - based transformer architecture. all the experiments were conducted using seven openly available hyperspectral datasets. our code is available at https : / / github. com / f - neumann77 / hyperkan.
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arxiv:2407.05278
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i argue that lhc may shed light on the nature of neutrino mass through the probe of the seesaw mechanism. the smoking gun signature is lepton number violation through the production of same sign lepton pairs, a collider analogy of the neutrinoless double beta decay. i discuss this in the context of l - r symmetric theories, which led originally to neutrino mass and the seesaw mechanism. a w _ r gauge boson with a mass in a few tev region could easily dominate neutrinoless double beta decay, and its discovery at lhc would have spectacular signatures of parity restoration and lepton number violation. moreover, lhc can measure the masses of the right - handed neutrinos and the right - handed leptonic mixing matrix, which could in turn be used to predict the rates for neutrinoless double decay and lepton flavor violating violating processes. the lr scale at the lhc energies offers great hope of observing these low energy processes in the present and upcoming experiments.
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arxiv:1012.4104
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