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1302.4021
|
The 2011 Periastron Passage of the Be Binary delta Scorpii
|
We describe the results of the world-wide observing campaign of the highly eccentric Be binary system delta Scorpii 2011 periastron passage which involved professional and amateur astronomers. Our spectroscopic observations provided a precise measurement of the system orbital period at 10.8092+/- 0.0005 years. Fitting of the He II 4686A line radial velocity curve determined the periastron passage time on 2011 July 3, UT 9:20 with a 0.9--day uncertainty. Both these results are in a very good agreement with recent findings from interferometry. We also derived new evolutionary masses of the binary components (13 and 8.2 Msun) and a new distance of 136 pc from the Sun, consistent with the HIPPARCOS parallax. The radial velocity and profile variations observed in the H_alpha line near the 2011 periastron reflected the interaction of the secondary component and the circumstellar disk around the primary component. Using these data, we estimated a disk radius of 150 Rsun. Our analysis of the radial velocity variations measured during the periastron passage time in 2000 and 2011 along with those measured during the 20th century, the high eccentricity of the system, and the presence of a bow shock-like structure around it suggest that delta Sco might be a runaway triple system. The third component should be external to the known binary and move on an elliptical orbit that is tilted by at least 40 degree with respect to the binary orbital plane for such a system to be stable and responsible for the observed long-term radial velocity variations.
|
[
"Physics Archive->astro-ph->astro-ph.SR"
] | 2013-02-17T01:26:04Z |
1411.5601
|
Bridging from particle to macroscopic scales in uniaxial magnetic gels
|
Connecting the different length scales of characterization is an important, but often very tedious task for soft matter systems. Here we carry out such a procedure for the theoretical description of anisotropic uniaxial magnetic gels. The so-far undetermined material parameters in a symmetry-based macroscopic hydrodynamic-like description are determined starting from a simplified mesoscopic particle-resolved model. This mesoscopic approach considers chain-like aggregates of magnetic particles embedded in an elastic matrix. Our procedure provides an illustrative background to the formal symmetry-based macroscopic description. There are presently other activities to connect such mesoscopic models as ours with more microscopic polymer-resolved approaches; together with these activities, our study complements a first attempt of scale-bridging from the microscopic to the macroscopic level in the characterization of magnetic gels.
|
[
"Physics Archive->cond-mat->cond-mat.soft"
] | 2014-11-20T16:50:00Z |
2004.10262
|
Continuity of Zero-Hitting Times of Bessel Processes and Welding Homeomorphisms of SLE$_\kappa$
|
We consider a family of Bessel Processes that depend on the starting point $x$ and dimension $\delta$, but are driven by the same Brownian motion. Our main result is that almost surely the first time a process hits $0$ is jointly continuous in $x$ and $\delta$, provided $\delta\le 0$. As an application, we show that the SLE($\kappa$) welding homeomorphism is continuous in $\kappa$ for $\kappa\in [0,4]$. Our motivation behind this is to study the well known problem of the continuity of SLE$_\kappa$ in $\kappa$. The main tool in our proofs is random walks with increments distributed as infinite mean Inverse-Gamma laws.
|
[
"Mathematics Archive->math.PR"
] | 2020-04-21T19:57:07Z |
hep-th/9509104
|
The Recoils of a Dynamical Mirror and the Decoherence of its Fluxes
|
In order to address the problem of the validity of the "background field approximation", we introduce a dynamical model for a mirror described by a massive quantum field. We then analyze the properties of the scattering of a massless field from this dynamical mirror and compare the results with the corresponding quantities evaluated using the original Davies Fulling model in which the mirror is represented by a boundary condition imposed on the massless field at its surface. We show that in certain circumstances, the recoils of the dynamical mirror induce decoherence effects which subsist even when the mass of the mirror is sent to infinity. In particular we study the case of the uniformly accelerated mirror and prove that, after a certain lapse of proper time, the decoherence effects inevitably dominate the physics of the quanta emitted forward. Then, the vanishing of the mean flux obtained in the Davies Fulling model is no longer found but replaced by a positive incoherent flux.
|
[
"Physics Archive->hep->hep-th"
] | 1995-09-20T12:53:24Z |
1211.0176
|
Joining relations under discrete uncertainty
|
In this paper we introduce and experimentally compare alternative algorithms to join uncertain relations. Different algorithms are based on specific principles, e.g., sorting, indexing, or building intermediate relational tables to apply traditional approaches. As a consequence their performance is affected by different features of the input data, and each algorithm is shown to be more efficient than the others in specific cases. In this way statistics explicitly representing the amount and kind of uncertainty in the input uncertain relations can be used to choose the most efficient algorithm.
|
[
"Computer Science Archive->cs.DB"
] | 2012-11-01T13:45:04Z |
2003.08373
|
Quantum Fisher information measurement and verification of the quantum Cram\'er-Rao bound in a solid-state qubit
|
The quantum Cram\'er-Rao bound sets a fundamental limit on the accuracy of unbiased parameter estimation in quantum systems, relating the uncertainty in determining a parameter to the inverse of the quantum Fisher information. We experimentally demonstrate near saturation of the quantum Cram\'er-Rao bound in the phase estimation of a solid-state spin system, provided by a nitrogen-vacancy center in diamond. This is achieved by comparing the experimental uncertainty in phase estimation with an independent measurement of the related quantum Fisher information. The latter is independently extracted from coherent dynamical responses of the system under weak parametric modulations, without performing any quantum-state tomography. While optimal parameter estimation has already been observed for quantum devices involving a limited number of degrees of freedom, our method offers a versatile and powerful experimental tool to explore the Cram\'er-Rao bound and the quantum Fisher information in systems of higher complexity, as relevant for quantum technologies.
|
[
"Physics Archive->quant-ph"
] | 2020-03-18T17:51:06Z |
2111.05031
|
Dynamics of atoms within atoms
|
Recent experiments with Bose-Einstein condensates have entered a regime in which thousands of ground-state condensate atoms fill the Rydberg-electron orbit. After the excitation of a single atom into a highly excited Rydberg state, scattering off the Rydberg electron sets ground-state atoms into motion, such that one can study the quantum-many-body dynamics of atoms moving within the Rydberg atom. Here we study this many-body dynamics using Gross-Pitaevskii and truncated Wigner theory. Our simulations focus in particular on the scenario of multiple sequential Rydberg excitations on the same Rubidium condensate which has become the standard tool to observe quantum impurity dynamics in Rydberg experiments. We investigate to what extent such experiments can be sensitive to details in the electron-atom interaction potential, such as the rapid radial modulation of the Rydberg molecular potential, or p-wave shape resonance. We demonstrate that both effects are crucial for the initial condensate response within the Rydberg orbit, but become less relevant for the density waves emerging outside the Rydberg excitation region at later times. Finally we explore the local dynamics of condensate heating. We find that it provides only minor corrections to the mean-field dynamics.
|
[
"Physics Archive->cond-mat->cond-mat.quant-gas",
"Physics Archive->physics->physics.atom-ph",
"Physics Archive->quant-ph"
] | 2021-11-09T10:16:49Z |
1804.06071
|
Patterns in random permutations avoiding some sets of multiple patterns
|
We consider a random permutation drawn from the set of permutations of length $n$ that avoid some given set of patterns of length 3. We show that the number of occurrences of another pattern $\sigma$ has a limit distribution, after suitable scaling. In several cases, the number is asymptotically normal; this contrasts to the cases of permutations avoiding a single pattern of length 3 studied in earlier papers.
|
[
"Mathematics Archive->math.CO",
"Mathematics Archive->math.PR"
] | 2018-04-17T06:48:19Z |
1211.0141
|
Rainbow connection number and the number of blocks
|
An edge-colored graph $G$ is rainbow connected if every pair of vertices of $G$ are connected by a path whose edges have distinct colors. The rainbow connection number $rc(G)$ of $G$ is defined to be the minimum integer $t$ such that there exists an edge-coloring of $G$ with $t$ colors that makes $G$ rainbow connected. For a graph $G$ without any cut vertex, i.e., a 2-connected graph, of order $n$, it was proved that $rc(G)\leq \lceil\frac n 2 \rceil$ and the bound is tight. In this paper, we prove that for a connected graph $G$ of order $n$ with cut vertices, $rc(G) \leq\frac{n+r-1} 2$, where $r$ is the number of blocks of $G$ with even orders, and the upper bound is tight. Moreover, we also obtain a tight upper bound for a bridgeless graph, i.e., a 2-edge-connected graph.
|
[
"Mathematics Archive->math.CO"
] | 2012-11-01T10:30:35Z |
1003.4769
|
African Dust Influence on Atlantic Hurricane Activity and the Peculiar Behaviour of Category 5 Hurricanes
|
We study the specific influence of African dust on each one of the categories of Atlantic hurricanes. By applying wavelet analysis, we find a strong decadal modulation of African dust on Category 5 hurricanes and an annual modulation on all other categories of hurricanes. We identify the formation of Category 5 hurricanes occurring mainly around the decadal minimum variation of African dust and in deep water areas of the Atlantic Ocean, where hurricane eyes have the lowest pressure. According to our results, future tropical cyclones will not evolve to Category 5 until the next decadal minimum that is, by the year 2015 +/- 2.
|
[
"Physics Archive->physics->physics.ao-ph"
] | 2010-03-24T22:47:11Z |
1311.1834
|
Pseudodifferentialoperatoren mit nichtglatten Koeffizienten auf Mannigfaltigkeiten
|
A generalization of differential operators are pseudodifferential operators which are used for reasoning about partial differential equations with variable coefficients. A lot of useful properties about classical pseudodifferential operators are already discovered by the works of H. Kumano-Go and L. H\"ormander. In this work, we like to transfer their ideas on those operators which symbols are merely H\"older-continous. We focus on the composition of operators, symbol smoothing and operators on manifolds.
|
[
"Mathematics Archive->math.AP"
] | 2013-11-07T21:59:53Z |
1807.01563
|
Scaling of submicrometric Turing patterns in concentrated growing systems
|
The wavelength of a periodic spatial structure of Turing type is an intrinsic property of the considered reaction-diffusion dynamics and we address the question of its control at the microscopic scale for given dynamical parameters. The direct simulation Monte Carlo method, initially introduced to simulate particle dynamics in rarefied gases, is adapted to the simulation of concentrated solutions. We perform simulations of a submicrometric Turing pattern with appropriate boundary conditions and show that taking into account the role of the solvent in the chemical mechanism allows us to control the wavelength of the structure. Typically, doubling the concentration of the solution leads to decreasing the wavelength by two. The results could be used to design materials with controled submicrometric properties in chemical engineering. They could also be considered as a possible interpretation of proportion preservation of embryos in morphogenesis.
|
[
"Physics Archive->nlin->nlin.PS"
] | 2018-07-04T13:21:52Z |
1608.01452
|
Weight-Lattice Discretization of Weyl-Orbit Functions
|
Weyl-orbit functions have been defined for each simple Lie algebra, and permit Fourier-like analysis on the fundamental region of the corresponding affine Weyl group. They have also been discretized, using a refinement of the coweight lattice, so that digitized data on the fundamental region can be Fourier-analyzed. The discretized orbit function has arguments that are redundant if related by the affine Weyl group, while its labels, the Weyl-orbit representatives, invoke the dual affine Weyl group. Here we discretize the orbit functions in a novel way, by using the weight lattice. A cleaner theory results, with symmetry between the arguments and labels of the discretized orbit functions. Orthogonality of the new discretized orbit functions is proved, and leads to the construction of unitary, symmetric matrices with Weyl-orbit-valued elements. For one type of orbit function, the matrix coincides with the Kac-Peterson modular $S$ matrix, important for Wess-Zumino-Novikov-Witten conformal field theory.
|
[
"Mathematics Archive->math.MP",
"Physics Archive->math-ph"
] | 2016-08-04T08:03:27Z |
1909.07075
|
Classification-Specific Parts for Improving Fine-Grained Visual Categorization
|
Fine-grained visual categorization is a classification task for distinguishing categories with high intra-class and small inter-class variance. While global approaches aim at using the whole image for performing the classification, part-based solutions gather additional local information in terms of attentions or parts. We propose a novel classification-specific part estimation that uses an initial prediction as well as back-propagation of feature importance via gradient computations in order to estimate relevant image regions. The subsequently detected parts are then not only selected by a-posteriori classification knowledge, but also have an intrinsic spatial extent that is determined automatically. This is in contrast to most part-based approaches and even to available ground-truth part annotations, which only provide point coordinates and no additional scale information. We show in our experiments on various widely-used fine-grained datasets the effectiveness of the mentioned part selection method in conjunction with the extracted part features.
|
[
"Computer Science Archive->cs.CV",
"Computer Science Archive->cs.LG"
] | 2019-09-16T09:13:47Z |
hep-th/0302056
|
Universal Ratios and Correlation Functions
|
We review some recent results concerning the quantitative analysis of the universality classes of two-dimensional statistical models near their critical point. We also discuss the exact calculation of the two--point correlation functions of disorder operators in a free theory of complex bosonic and fermionic field, correlators ruled by a Painleve differential equation.
|
[
"Physics Archive->hep->hep-th"
] | 2003-02-08T16:54:13Z |
1401.5643
|
Hole burning and higher order photon effects in attosecond light-atom interaction
|
We have performed calculations of attosecond laser-atom interactions for laser intensities where interesting two and three photon effects become relevant. In particular, we examine the case of "hole burning" in the initial orbital. Hole burning is present when the laser pulse duration is shorter than the classical radial period because the electron preferentially absorbs the photon near the nucleus. We also examine how 3 photon Raman process can lead to a time delay in the outgoing electron for the energy near one photon absorption. For excitation out of the hydrogen $2s$ state, an intensity of $2.2\times 10^{16}$ W/cm$^2$ leads to a 6 attosecond delay of the outgoing electron. We argue that this delay is due to the hole burning in the initial state.
|
[
"Physics Archive->physics->physics.atom-ph"
] | 2014-01-22T12:33:59Z |
1707.02458
|
Equilibrium stability for non-uniformly hyperbolic systems
|
We prove that for a wide family of non-uniformly hyperbolic maps and hyperbolic potentials we have equilibrium stability, i.e. the equilibrium states depend continuously on the dynamics and the potential. For this we deduce that the topological pressure is continuous as a function of the dynamics and the potential. We also prove the existence of finitely many ergodic equilibrium states for non-uniformly hyperbolic skew products and hyperbolic H\"older continuous potentials. Finally we show that these equilibrium states vary continuously in the weak$^\ast$ topology within such systems.
|
[
"Mathematics Archive->math.DS"
] | 2017-07-08T16:14:01Z |
0801.0608
|
SMA Imaging of the Maser Emission from the H30$\alpha$ Radio Recombination Line in MWC349A
|
We used the Submillimeter Array to map the angular distribution of the H30$\alpha$ recombination line (231.9 GHz) in the circumstellar region of the peculiar star MWC349A. The resolution was $1\farcs2$, but because of high signal-to-noise ratio we measured the positions of all maser components to accuracies better than $0\farcs01$, at a velocity resolution of $1 kms$. The two strongest maser components (called high velocity components) at velocities near -14 and $32 kms$ are separated by $0\farcs048 \pm 0\farcs001$ (60 AU) along a position angle of $102 \pm 1\arcdeg$. The distribution of maser emission at velocities between and beyond these two strongest components were also provided. The continuum emission lies at the center of the maser distribution to within 10 mas. The masers appear to trace a nearly edge-on rotating disk structure, reminiscent of the water masers in Keplerian rotation in the nuclear accretion disk of the galaxy NGC4258. However, the maser components in MWC349A do not follow a simple Keplerian kinematic prescription with $v \sim r^{-1/2}$, but have a larger power law index. We explore the possibility that the high velocity masers trace spiral density or shock waves. We also emphasize caution in the interpretation of relative centroid maser positions where the maser is not clearly resolved in position or velocity, and we present simulations that illustrate the range of applicability of the centroiding method.
|
[
"Physics Archive->astro-ph"
] | 2008-01-04T15:08:35Z |
2012.09739
|
Rounding error using low precision approximate random variables
|
For numerical approximations to stochastic differential equations using the Euler-Maruyama scheme, we propose incorporating approximate random variables computed using low precisions, such as single and half precision. We propose and justify a model for the rounding error incurred, and produce an average case error bound for two and four way differences, appropriate for regular and nested multilevel Monte Carlo estimations. By considering the variance structure of multilevel Monte Carlo correction terms in various precisions with and without a Kahan compensated summation, we compute the potential speed ups offered from the various precisions. We find single precision offers the potential for approximate speed improvements by a factor of 7 across a wide span of discretisation levels. Half precision offers comparable improvements for several levels of coarse simulations, and even offers improvements by a factor of 10-12 for the very coarsest few levels.
|
[
"Computer Science Archive->cs.NA",
"Mathematics Archive->math.NA"
] | 2020-12-17T16:59:39Z |
2012.05274
|
Topological Protection of Coherence in Noisy Open Quantum Systems
|
We consider topological protection mechanisms in dissipative quantum systems in the presence of quenched disorder, with the intent to prolong coherence times of qubits. The physical setting is a network of qubits and dissipative cavities whose coupling parameters are tunable, such that topological edge states can be stabilized. The evolution of a fiducial qubit is entirely determined by a non-Hermitian Hamiltonian which thus emerges from a bona-fide physical process. It is shown how even in the presence of disorder winding numbers can be defined and evaluated in real space, as long as certain symmetries are preserved. Hence we can construct the topological phase diagrams of noisy open quantum models, such as the non-Hermitian disordered Su-Schrieffer- Heeger dimer model and a trimer model that includes longer-range couplings. In the presence of competing disorder parameters, interesting re-entrance phenomena of topologically non-trivial sectors are observed. This means that in certain parameter regions, increasing disorder drastically increases the coherence time of the fiducial qubit.
|
[
"Physics Archive->quant-ph"
] | 2020-12-09T19:22:45Z |
2205.10568
|
BlockDFL: A Blockchain-based Fully Decentralized Federated Learning Framework
|
Federated learning (FL) enables collaborative training of machine learning models while protecting the privacy of data. Traditional FL heavily relies on a trusted centralized server. It is vulnerable to poisoning attacks, the sharing of raw model updates puts the private training data under the risk of being reconstructed, and it suffers from an efficiency problem due to heavy communication cost. Although decentralized FL eliminates the central dependence, it may worsen the other problems due to insufficient constraints on the behavior of participants and distributed consensus on the global model update. In this paper, we propose a blockchain-based fully decentralized peer-to-peer (P2P) framework for FL, called BlockDFL for short. It leverages blockchain to force participants to behave well. It integrates gradient compression and our designed voting mechanism to coordinate decentralized FL among peer participants without mutual trust, while preventing data from being reconstructed from transmitted model updates. Extensive experiments conducted on two real-world datasets exhibit that BlockDFL obtains competitive accuracy compared to centralized FL and can defend poisoning attacks while achieving efficiency and scalability. Especially when the proportion of malicious participants is as high as 40%, BlockDFL can still preserve the accuracy of FL, outperforming existing fully decentralized FL frameworks based on blockchain.
|
[
"Computer Science Archive->cs.DC"
] | 2022-05-21T11:34:57Z |
0910.4869
|
Reifenberg Parameterizations for Sets with Holes
|
We extend the proof of Reifenberg's Topological Disk Theorem to allow the case of sets with holes, and give sufficient conditions on a set $E$ for the existence of a bi-Lipschitz parameterization of $E$ by a $d$-dimensional plane or smooth manifold. Such a condition is expressed in terms of square summability for the P. Jones numbers $\beta_1(x,r)$. In particular, it applies in the locally Ahlfors-regular case to provide very big pieces of bi-Lipschitz images of $\R^d$.
|
[
"Mathematics Archive->math.CA"
] | 2009-10-26T13:02:35Z |
2007.02025
|
Robust Prediction of Punctuation and Truecasing for Medical ASR
|
Automatic speech recognition (ASR) systems in the medical domain that focus on transcribing clinical dictations and doctor-patient conversations often pose many challenges due to the complexity of the domain. ASR output typically undergoes automatic punctuation to enable users to speak naturally, without having to vocalise awkward and explicit punctuation commands, such as "period", "add comma" or "exclamation point", while truecasing enhances user readability and improves the performance of downstream NLP tasks. This paper proposes a conditional joint modeling framework for prediction of punctuation and truecasing using pretrained masked language models such as BERT, BioBERT and RoBERTa. We also present techniques for domain and task specific adaptation by fine-tuning masked language models with medical domain data. Finally, we improve the robustness of the model against common errors made in ASR by performing data augmentation. Experiments performed on dictation and conversational style corpora show that our proposed model achieves ~5% absolute improvement on ground truth text and ~10% improvement on ASR outputs over baseline models under F1 metric.
|
[
"Computer Science Archive->cs.CL",
"Computer Science Archive->cs.SD",
"Electrical Engineering and Systems Science Archive->eess.AS"
] | 2020-07-04T07:15:13Z |
quant-ph/0002042
|
On the Non-Orthonormality of Lippmann-Schwinger-Low States
|
It is pointed out that for a general short-ranged potential the Lippmann-Schwinger-Low scattering state $|\psi^L_k>$ does not strictly satisfy the Schrodinger eigen equation, and the pair $|\psi^L_n>$, $|\psi^L_k>$ is mutually nonorthogonal if $E_n=E_k$. For this purpose, we carefully use an infinitesimal adiabatic parameter $\epsilon$, a nonlinear relation among transition amplitudes, and a separable interaction as illustration.
|
[
"Physics Archive->quant-ph"
] | 2000-02-15T05:58:18Z |
1406.5904
|
Quantum Wronskian approach to six-point gluon scattering amplitudes at strong coupling
|
We study the six-point gluon scattering amplitudes in N=4 super Yang-Mills theory at strong coupling based on the twisted Z_4-symmetric integrable model. The lattice regularization allows us to derive the associated thermodynamic Bethe ansatz (TBA) equations as well as the functional relations among the Q-/T-/Y-functions. The quantum Wronskian relation for the Q-/T-functions plays an important role in determining a series of the expansion coefficients of the T-/Y-functions around the UV limit, including the dependence on the twist parameter. Studying the CFT limit of the TBA equations, we derive the leading analytic expansion of the remainder function for the general kinematics around the limit where the dual Wilson loops become regular-polygonal. We also compare the rescaled remainder functions at strong coupling with those at two, three and four loops, and find that they are close to each other along the trajectories parameterized by the scale parameter of the integrable model.
|
[
"Physics Archive->hep->hep-th"
] | 2014-06-23T13:39:27Z |
1606.07007
|
Quantum State Reconstruction of an Oscillator Network in an Optomechanical Setting
|
We introduce a scheme to reconstruct an arbitrary quantum state of a mechanical oscillator network. We assume that a single element of the network is coupled to a cavity field via a linearized optomechanical interaction, whose time dependence is controlled by a classical driving field. By designing a suitable interaction profile, we show how the statistics of an arbitrary mechanical quadrature can be encoded in the cavity field, which can then be measured. We discuss the important special case of Gaussian state reconstruction, and study numerically the effectiveness of our scheme for a finite number of measurements. Finally, we speculate on possible routes to extend our ideas to the regime of single-photon optomechanics.
|
[
"Physics Archive->quant-ph"
] | 2016-06-22T16:41:46Z |
1010.2698
|
Reheating via a generalized non-minimal coupling of curvature to matter
|
In this work one shows that a generalized non-minimal coupling between geometry and matter is compatible with Starobinsky inflation and leads to a successful process of preheating, a reheating scenario based on the production of massive particles via parametric resonance. The model naturally extends the usual preheating mechanism, which resorts to an {\it ad-hoc} scalar curvature-dependent mass term for a scalar field $\chi$, and also encompasses a previously studied preheating channel based upon a non-standard kinetic term.
|
[
"Physics Archive->gr-qc"
] | 2010-10-13T16:43:47Z |
1309.1642
|
Measurement of electrons from heavy-flavour hadron decays in pp and p-Pb collisions with ALICE
|
ALICE measured electrons from inclusive heavy-flavour hadron decays and beauty-hadron decays at mid-rapidity in pp collisions at \sqrt{s} = 7 TeV and 2.76 TeV and p-Pb collisions at \sqrt{s_{NN}} = 5.02 TeV. For both pp collision energies, p_T-differential electron production cross sections are presented and compared to pQCD predictions. For p-Pb collisions, the p_T-dependent nuclear modification factor of electrons from inclusive heavy-flavour hadron decays is presented.
|
[
"Physics Archive->hep->hep-ex",
"Physics Archive->nucl->nucl-ex"
] | 2013-09-06T13:55:37Z |
hep-th/0007196
|
New vacua for Yang-Mills theory on a 3-torus
|
In this thesis we discuss recent new insights in the structure of the moduli space of flat connections of Yang-Mills theory on a 3-torus. Chapter 2 discusses the computation of Witten's index for 4-dimensional gauge theories, and the paradox that arises in comparing various computations. This was resolved by the discovery that for orthogonal and exceptional gauge groups, periodic flat connections exist that are contained in seperate, disconnected components of the moduli space. Chapter 3 and 4 discuss some aspects of the construction of holonomies parametrising vacua on such disconnected components. Chapter 5 demonstrates a construction of vacua and holonomies for gauge theories with classical groups, with non-periodic (twisted) boundary conditions, using an orientifold description. The new solutions with exceptional and orthogonal gauge groups also occur in string theory. Chapter 6, containing previously unpublished material, shows that they can be realised within heterotic string theories as asymmetric orbifolds. The presence of string winding states modifies the analysis for the gauge theory in a crucial way, eliminating many possibilities. The remaining ones are related by string dualities to known and new theories.
|
[
"Physics Archive->hep->hep-th"
] | 2000-07-25T13:24:47Z |
1405.2214
|
Open Quantum Random Walks: reducibility, period, ergodic properties
|
We study the analogues of irreducibility, period, and communicating classes for open quantum random walks, as defined by Attal et al. (J. Stat. Phys., 2012). We recover results similar to the standard ones for Markov chains, in terms of ergodic behavior, decomposition into irreducible subsystems, and characterization of stationary states.
|
[
"Mathematics Archive->math.PR"
] | 2014-05-09T12:21:33Z |
1508.04508
|
Limits of Jordan Lie subalgebras
|
Let g be a simple Lie algebra of rank n over C. We show that the n-dimensional abelian ideals of a Borel subalgebra of g are limits of Jordan Lie subalgebras. Combining this with a classical result by Kostant, we show that the g-module spanned by all n-dimensional abelian Lie subalgebras of g is actually spanned by the Jordan Lie subalgebras.
|
[
"Mathematics Archive->math.RT"
] | 2015-08-19T03:02:32Z |
0809.0805
|
Baryons and Baryonic Matter in Holographic QCD from Superstring
|
We study baryons and baryonic matter in holographic QCD using a D4/D8/$\bar{\rm D8}$ multi-D-brane system in the superstring theory. We obtain the chiral soliton solution for baryons in the four-dimensional meson theory derived from the multi-D-brane system. For the analysis of finite baryon-density matter, we investigate the chiral soliton on $S^3$ in holographic QCD, and find the delocalization of the soliton, i.e., the swelling of baryons in dense matter.
|
[
"Physics Archive->hep->hep-th"
] | 2008-09-04T13:04:23Z |
astro-ph/9806105
|
Non-Gaussian signature of weak gravitational lensing in the CMB
|
Inflationary cosmologies predict Gaussian primordial fluctuations, but subsequent gravitational lensing of the CMB disturbs its Gaussianity. Knowledge of the specific signature of lensing is necessary to distinguish a lensed Gaussian sky from an intrinsically non-Gaussian one. In this paper we investigate the pattern of non-Gaussian features in the CMB resulting from gravitational lensing, both analytically and numerically. We describe the lensed CMB temperature distribution using the formalism of generating functionals and obtain the complete picture of emerging non-Gaussian effects. To test for the signature of lensing in practice, we propose a scale-dependent statistic based on cumulants of the CMB temperature, and we compute that statistic numerically for typical inflationary models. The effect is expected to be most significant at angular scales $\sim 10^\prime$ and its magnitude is within observational capabilities of future satellite missions.
|
[
"Physics Archive->astro-ph"
] | 1998-06-08T00:56:13Z |
astro-ph/9405031
|
The X-ray Spectrum of Soft Gamma Repeater 1806-20
|
Soft Gamma Repeaters (SGRs) are a class of rare, high-energy galactic transients that have episodes of short (~0.1 sec), soft (~30 keV), intense (~100 Crab), gamma-ray bursts. We report an analysis of the x-ray emission from 95 SGR1806-20 events observed by the International Cometary Explorer. The spectral shape remains remarkably constant for bursts that differ in intensity by a range of 50. Below 15 keV the number spectrum falls off rapidly such that we can estimate the total intensity of the events. Assuming that SGR1806-20 is associated with the supernova remnant G10.0-0.3 (Kulkarni and Frail, Murakami \etal), the brightest events had a total luminosity of ~1.8 x 10^42 erg sec^-1, a factor of 2 x 10^4 above the Eddington limit. A third of the emission was above 30 keV. There are at least three processes that are consistent with the spectral rollover below 15 keV. (1)The rollover is consistent with some forms of self absorption. Typical thermal temperatures are ~20 keV and require an emitting surface with a radius between 10 and 50 km. The lack of spectral variability implies that only the size of the emitting surface varies between events. If the process is thermal synchrotron the required magnetic field might be too small to confine the plasma against the super Eddington flux. (2)The low energy rollover could be due to photoelectric absorption by ~10^24 Hydrogen atoms cm^-2 of neutral material with a cosmic abundance assuming a continuum similar to TB with T= ~22 keV. (3) Emission in the two lowest harmonics from a 1.3 x 10^12 Gauss field would appear as Doppler broadened lines and fall off rapidly below 15 keV.
|
[
"Physics Archive->astro-ph"
] | 1994-05-12T14:17:01Z |
2303.17994
|
Helson-Lowdenslager and de Branges type theorems in the setting of continuous rotationally symmetric norms
|
A Helson-Lowdenslager type result has been proved by Chen in the context of Lebesgue spaces of the unit circle equipped with a continuous rotationally symmetric norm by studying the simply invariant subspaces of the operator of multiplication by the coordinate function $z$. In this paper, we generalize Chen's result by obtaining a description of simply invariant subspaces for multiplication by $z^n$. A de Branges type result is also proved for Hardy spaces equipped with continuous rotationally symmetric norms.
|
[
"Mathematics Archive->math.FA"
] | 2023-03-31T12:11:21Z |
1806.00299
|
Fast Artificial Immune Systems
|
Various studies have shown that characteristic Artificial Immune System (AIS) operators such as hypermutations and ageing can be very efficient at escaping local optima of multimodal optimisation problems. However, this efficiency comes at the expense of considerably slower runtimes during the exploitation phase compared to standard evolutionary algorithms. We propose modifications to the traditional `hypermutations with mutation potential' (HMP) that allow them to be efficient at exploitation as well as maintaining their effective explorative characteristics. Rather than deterministically evaluating fitness after each bitflip of a hypermutation, we sample the fitness function stochastically with a `parabolic' distribution which allows the `stop at first constructive mutation' (FCM) variant of HMP to reduce the linear amount of wasted function evaluations when no improvement is found to a constant. By returning the best sampled solution during the hypermutation, rather than the first constructive mutation, we then turn the extremely inefficient HMP operator without FCM, into a very effective operator for the standard Opt-IA AIS using hypermutation, cloning and ageing. We rigorously prove the effectiveness of the two proposed operators by analysing them on all problems where the performance of HPM is rigorously understood in the literature. %
|
[
"Computer Science Archive->cs.NE"
] | 2018-06-01T11:54:20Z |
1806.07595
|
Non-geometric States in a Holographic Conformal Field Theory
|
In the AdS$_3$/CFT$_2$ correspondence, we find some conformal field theory (CFT) states that have no bulk description by the Ba\~nados geometry. We elaborate the constraints for a CFT state to be geometric, i.e., having a dual Ba\~nados metric, by comparing the order of central charge of the entanglement/R\'enyi entropy obtained respectively from the holographic method and the replica trick in CFT. We find that the geometric CFT states fulfill Bohr's correspondence principle by reducing the quantum KdV hierarchy to its classical counterpart. We call the CFT states that satisfy the geometric constraints geometric states, and otherwise non-geometric states. We give examples of both the geometric and non-geometric states, with the latter case including the superposition states and descendant states.
|
[
"Physics Archive->gr-qc",
"Physics Archive->hep->hep-th"
] | 2018-06-20T07:54:41Z |
0711.0315
|
Measuring and Monitoring Grid Resource Utilisation
|
Effective resource utilisation monitoring and highly granular yet adaptive measurements are prerequisites for a more efficient Grid scheduler. We present a suite of measurement applications able to monitor per-process resource utilisation, and a customisable tool for emulating observed utilisation models.
|
[
"Computer Science Archive->cs.DC"
] | 2007-11-02T14:12:27Z |
0807.2322
|
On phase transition signal in inelastic collision
|
The paper is devoted to retrieval of the first order phase transition signal in the inelastic collisions. The primary intent is to show that the experimentally observable signal exist iff the multiplicity is sufficiently large. We discuss corresponding phenomenology from point of view of the experiment.
|
[
"Physics Archive->hep->hep-ph"
] | 2008-07-15T08:56:34Z |
1805.04132
|
Boosting up Scene Text Detectors with Guided CNN
|
Deep CNNs have achieved great success in text detection. Most of existing methods attempt to improve accuracy with sophisticated network design, while paying less attention on speed. In this paper, we propose a general framework for text detection called Guided CNN to achieve the two goals simultaneously. The proposed model consists of one guidance subnetwork, where a guidance mask is learned from the input image itself, and one primary text detector, where every convolution and non-linear operation are conducted only in the guidance mask. On the one hand, the guidance subnetwork filters out non-text regions coarsely, greatly reduces the computation complexity. On the other hand, the primary text detector focuses on distinguishing between text and hard non-text regions and regressing text bounding boxes, achieves a better detection accuracy. A training strategy, called background-aware block-wise random synthesis, is proposed to further boost up the performance. We demonstrate that the proposed Guided CNN is not only effective but also efficient with two state-of-the-art methods, CTPN and EAST, as backbones. On the challenging benchmark ICDAR 2013, it speeds up CTPN by 2.9 times on average, while improving the F-measure by 1.5%. On ICDAR 2015, it speeds up EAST by 2.0 times while improving the F-measure by 1.0%.
|
[
"Computer Science Archive->cs.CV",
"Computer Science Archive->cs.LG"
] | 2018-05-10T18:51:19Z |
cs/0506028
|
Neyman-Pearson Detection of Gauss-Markov Signals in Noise: Closed-Form Error Exponent and Properties
|
The performance of Neyman-Pearson detection of correlated stochastic signals using noisy observations is investigated via the error exponent for the miss probability with a fixed level. Using the state-space structure of the signal and observation model, a closed-form expression for the error exponent is derived, and the connection between the asymptotic behavior of the optimal detector and that of the Kalman filter is established. The properties of the error exponent are investigated for the scalar case. It is shown that the error exponent has distinct characteristics with respect to correlation strength: for signal-to-noise ratio (SNR) >1 the error exponent decreases monotonically as the correlation becomes stronger, whereas for SNR <1 there is an optimal correlation that maximizes the error exponent for a given SNR.
|
[
"Computer Science Archive->cs.IT",
"Mathematics Archive->math.IT"
] | 2005-06-08T22:43:07Z |
2006.13011
|
Joint Left Atrial Segmentation and Scar Quantification Based on a DNN with Spatial Encoding and Shape Attention
|
We propose an end-to-end deep neural network (DNN) which can simultaneously segment the left atrial (LA) cavity and quantify LA scars. The framework incorporates the continuous spatial information of the target by introducing a spatially encoded (SE) loss based on the distance transform map. Compared to conventional binary label based loss, the proposed SE loss can reduce noisy patches in the resulting segmentation, which is commonly seen for deep learning-based methods. To fully utilize the inherent spatial relationship between LA and LA scars, we further propose a shape attention (SA) mechanism through an explicit surface projection to build an end-to-end-trainable model. Specifically, the SA scheme is embedded into a two-task network to perform the joint LA segmentation and scar quantification. Moreover, the proposed method can alleviate the severe class-imbalance problem when detecting small and discrete targets like scars. We evaluated the proposed framework on 60 LGE MRI data from the MICCAI2018 LA challenge. For LA segmentation, the proposed method reduced the mean Hausdorff distance from 36.4 mm to 20.0 mm compared to the 3D basic U-Net using the binary cross-entropy loss. For scar quantification, the method was compared with the results or algorithms reported in the literature and demonstrated better performance.
|
[
"Computer Science Archive->cs.CV",
"Electrical Engineering and Systems Science Archive->eess.IV"
] | 2020-06-23T13:55:29Z |
hep-ph/0201008
|
Zeroes of the Neutrino Mass Matrix
|
We assume there to be precisely three left-handed neutrino states whose Majorana masses are generated by an unspecified mechanism. Were CP conserved, the symmetric neutrino mass matrix M would be real and all six of its distinct entries could be experimentally determined. But CP is not conserved so that M is likely to be complex. As a result, not all nine of its convention-independent real parameters can be determined without an appeal to theory. Thus we examine the possibility that a restricted class of neutrino mass matrices may suffice to describe current data, namely those complex symmetric matrices several of whose entries vanish. We find that there are seven acceptable textures with two independent zeroes, and we explore their contrasting phenomenological implications. Textures with more than two independent zeroes appear to be excluded by experiment.
|
[
"Physics Archive->hep->hep-ph"
] | 2002-01-02T21:00:06Z |
0912.5119
|
Barnes type multiple q-zeta functions and q-Euler polynomials
|
The Barnes multiple zeta function is useful to study in the number theory and Knot thoey and Mathematical Physics. In this paper we consider q-extension of Barnes type multiple zeta function and we also construct the q-extension of Euler polynomials of higher order
|
[
"Mathematics Archive->math.NT"
] | 2009-12-28T01:57:23Z |
1109.2324
|
A study of stability analysis of pyroclastic covers based on electrical resistivity measurements
|
Usually, the degree of stability of a slope is quantified by the Factor of Safety whose values depend on physical and mechanical soil properties analyzed on samples of much reduced sizes or referring to very small soil volumes around porous probes. To overcome the limit of punctual information, we propose a semi-empirical approach based on the use of geophysical methods and the employment of a geophysical Factor of Safety recently introduced by the authors in terms of local resistivities and slope angles. In this paper, we show an application of our proposal on a test area of about 2000 m2 on Sarno Mountains (Campania Region - Southern Italy), where shallow landslides involving pyroclastic soils periodically occur triggered by critical rainfall events. Starting from two resistivity tomography surveys performed on the test area in autumn and spring, we obtained maps of the geophysical Factor of Safety at different depths for the two seasons. We also estimated the values of the Factor of Safety by using the infinite slope model in the dry and saturated scenario. A comparison between the values of the geophysical and geotechnical Factor of Safety shows advantages and disadvantages of our approach.
|
[
"Physics Archive->physics->physics.geo-ph"
] | 2011-09-11T16:10:55Z |
0901.3912
|
Large almost monochromatic subsets in hypergraphs
|
We show that for all $\ell$ and $\epsilon>0$ there is a constant $c=c(\ell,\epsilon)>0$ such that every $\ell$-coloring of the triples of an $N$-element set contains a subset $S$ of size $c\sqrt{\log N}$ such that at least $1-\epsilon$ fraction of the triples of $S$ have the same color. This result is tight up to the constant $c$ and answers an open question of Erd\H{o}s and Hajnal from 1989 on discrepancy in hypergraphs. For $\ell \geq 4$ colors, it is known that there is an $\ell$-coloring of the triples of an $N$-element set whose largest monochromatic subset has cardinality only $\Theta(\log \log N)$. Thus, our result demonstrates that the maximum almost monochromatic subset that an $\ell$-coloring of the triples must contain is much larger than the corresponding monochromatic subset. This is in striking contrast with graphs, where these two quantities have the same order of magnitude. To prove our result, we obtain a new upper bound on the $\ell$-color Ramsey numbers of complete multipartite 3-uniform hypergraphs, which answers another open question of Erd\H{o}s and Hajnal.
|
[
"Mathematics Archive->math.CO"
] | 2009-01-25T17:28:45Z |
1303.0096
|
Recent Belle results in quarkonium physics
|
We review selected recent Belle results in quarkonium physics, that include precision measurement of the eta_b(1S) parameters, evidence for the eta_b(2S); evidence for the psi_2(1D); observation of the psi(4040) and psi(4160) transitions to J/psi eta with anomalously high rates; observation of the Upsilon(5S) transitions to Upsilon(1D)pi+pi- and Upsilon(1S,2S)eta. The low excitations of charmonium and bottomonium are in agreement with the Lattice QCD and effective theories calculations, while high excitations show unexpected properties.
|
[
"Physics Archive->hep->hep-ex",
"Physics Archive->hep->hep-ph"
] | 2013-03-01T06:40:26Z |
1206.4542
|
Infinite Dimensional Bicomplex Spectral Decomposition Theorem
|
This paper presents a bicomplex version of the Spectral Decomposition Theorem on infinite dimensional bicomplex Hilbert spaces. In the process, the ideas of bounded linear operators, orthogonal complements and compact operators on bicomplex Hilbert spaces are introduced and treated in relation with the classical Hilbert space $M'$ imbedded in any bicomplex Hilbert space $M$.
|
[
"Mathematics Archive->math.FA"
] | 2012-06-19T17:32:31Z |
2307.15369
|
Measurement of leading charged-particle jet properties in p--Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV with ALICE
|
Jets are collimated sprays of particles produced from the fragmentation and hadronization of hard-scattered partons in high energy hadronic and nuclear collisions. Jet properties are sensitive to details of parton showering processes and are expected to be modified in the presence of a dense partonic medium. Measurement of intra-jet properties in p--Pb collisions will help to investigate cold nuclear matter effects and enrich our current understanding of particle production in such collision systems. In this work, we present the measurement of leading charged-particle jet properties, namely the mean charged-particle multiplicity and the fragmentation functions, in the range of jet $p_{\rm T}$ 10 -- 100 GeV/c at midrapidity in minimum bias p--Pb collisions at $\sqrt{s_{\rm NN}}$ = 5.02 TeV with ALICE. Results are compared with theoretical model predictions.
|
[
"Physics Archive->hep->hep-ex",
"Physics Archive->nucl->nucl-ex"
] | 2023-07-28T07:39:37Z |
2112.04407
|
Good action of a nilpotent group with regular orbits
|
Suppose that $A$ is a finite nilpotent group of odd order acting good in the sense of \cite{EGJ} on the group $G$ of odd order. Under some additional assumptions we prove that the Fitting height of $G$ is bounded above by the sum of the numbers of primes dividing $|A|$ and $|C_G(A)|$ counted with multiplicities.
|
[
"Mathematics Archive->math.GR"
] | 2021-12-08T16:52:28Z |
1607.06335
|
Admissible Hierarchical Clustering Methods and Algorithms for Asymmetric Networks
|
This paper characterizes hierarchical clustering methods that abide by two previously introduced axioms -- thus, denominated admissible methods -- and proposes tractable algorithms for their implementation. We leverage the fact that, for asymmetric networks, every admissible method must be contained between reciprocal and nonreciprocal clustering, and describe three families of intermediate methods. Grafting methods exchange branches between dendrograms generated by different admissible methods. The convex combination family combines admissible methods through a convex operation in the space of dendrograms, and thirdly, the semi-reciprocal family clusters nodes that are related by strong cyclic influences in the network. Algorithms for the computation of hierarchical clusters generated by reciprocal and nonreciprocal clustering as well as the grafting, convex combination, and semi-reciprocal families are derived using matrix operations in a dioid algebra. Finally, the introduced clustering methods and algorithms are exemplified through their application to a network describing the interrelation between sectors of the United States (U.S.) economy.
|
[
"Computer Science Archive->cs.LG",
"Statistics Archive->stat.ML"
] | 2016-07-21T14:22:12Z |
quant-ph/0502077
|
Scaling of running time of quantum adiabatic algorithm for propositional satisfiability
|
We numerically study quantum adiabatic algorithm for the propositional satisfiability. A new class of previously unknown hard instances is identified among random problems. We numerically find that the running time for such instances grows exponentially with their size. Worst case complexity of quantum adiabatic algorithm therefore seems to be exponential.
|
[
"Physics Archive->quant-ph"
] | 2005-02-14T09:25:07Z |
1202.6553
|
OPE in planar QCD from integrability
|
We consider the operator product expansion of local single-trace operators composed of the self-dual components of the field strength tensor in planar QCD. Using the integrability of the one-loop matrix of anomalous dimensions of such operators, we obtain a determinant expression for certain tree-level structure constants in the OPE.
|
[
"Mathematics Archive->math.MP",
"Physics Archive->hep->hep-th",
"Physics Archive->math-ph"
] | 2012-02-29T14:15:22Z |
1707.01663
|
The Hopfield-Kerr model and analogue black hole radiation in dielectrics
|
In the context of the interaction between the electromagnetic field and a dielectric dispersive lossless medium, we present a non-linear version of the relativistically covariant Hopfield model, which is suitable for the description of a dielectric Kerr perturbation propagating in a dielectric medium. The non-linearity is introduced in the Lagrangian through a self-interacting term proportional to the fourth power of the polarization field. We find an exact solution for the nonlinear equations describing a propagating perturbation in the dielectric medium. Furthermore the presence of an analogue Hawking effect, as well as the thermal properties of the model, are discussed, confirming and improving the results achieved in the scalar case.
|
[
"Physics Archive->gr-qc",
"Physics Archive->hep->hep-th"
] | 2017-07-06T07:39:30Z |
2207.10677
|
The first string-derived eclectic flavor model with realistic phenomenology
|
Eclectic flavor groups arising from string compactifications combine the power of modular and traditional flavor symmetries to address the flavor puzzle. This top-down scheme determines the representations and modular weights of all matter fields, imposing strict constraints on the structure of the effective potential, which result in controlled corrections. We study the lepton and quark flavor phenomenology of an explicit, potentially realistic example model based on a T6/Z3xZ3 orbifold compactification of the heterotic string that gives rise to an Omega(2) eclectic flavor symmetry. We find that the interplay of flavon alignment and the localization of the modulus in the vicinity of a symmetry-enhanced point leads to naturally protected fermion mass hierarchies, favoring normal-ordered neutrino masses arising from a see-saw mechanism. We show that our model can reproduce all observables in the lepton sector with a small number of parameters and deliver predictions for so far undetermined neutrino observables. Furthermore, we extend the fit to quarks and find that Kaehler corrections are instrumental in obtaining a successful simultaneous fit to the quark and lepton sectors.
|
[
"Physics Archive->hep->hep-ph",
"Physics Archive->hep->hep-th"
] | 2022-07-21T18:00:01Z |
0711.1254
|
Gauss-Codazzi Formalism to Braneworld Scenario within Brans-Dicke Theory
|
We apply the Gauss-Codacci formalism to brane worlds scenario within the framework of Brans-Dicke gravity. The compactification is taken from six to five dimensions in order to formalize brane-world models with hybrid compactification in scalar-tensor theories.
|
[
"Physics Archive->hep->hep-th"
] | 2007-11-08T12:17:05Z |
1304.0614
|
The BPS spectrum of the 4d N=2 SCFT's H_1, H_2, D_4, E_6, E_7, E_8
|
Extending results of arXiv:1112.3984, we show that all rank 1 N=2 SCFT's in the sequence H_1, H_2, D_4 E_6, E_7, E_8 have canonical finite BPS chambers containing precisely 2 h(F)=12(Delta-1) hypermultiplets. The BPS spectrum of the canonical BPS chambers saturates the conformal central charge c, and satisfies some intriguing numerology.
|
[
"Physics Archive->hep->hep-th"
] | 2013-04-02T12:27:03Z |
0902.1165
|
Finite element methods for a bi-wave equation modeling d-wave superconductors
|
In this paper we develop two conforming finite element methods for a fourth order bi-wave equation arising as a simplified Ginzburg-Landau-type model for d-wave superconductors in absence of applied magnetic field. Unlike the biharmonic operator $\Delta^2$, the bi-wave operator $\Box^2$ is not an elliptic operator, so the energy space for the bi-wave equation is much larger than the energy space for the biharmonic equation. This then makes it possible to construct low order conforming finite elements for the bi-wave equation. However, the existence and construction of such finite elements strongly depends on the mesh. In the paper, we first characterize mesh conditions which allow and not allow construction of low order conforming finite elements for approximating the bi-wave equation. We then construct a cubic and a quartic conforming finite element. It is proved that both elements have the desired approximation properties, and give optimal order error estimates in the energy norm, suboptimal (and optimal in some cases) order error estimates in the $H^1$ and $L^2$ norm. Finally, numerical experiments are presented to guage the efficiency of the proposed finite element methods and to validate the theoretical error bounds.
|
[
"Mathematics Archive->math.NA"
] | 2009-02-06T20:17:04Z |
1507.03994
|
Limits on thermal variations in a dozen quiescent neutron stars over a decade
|
In quiescent low-mass X-ray binaries (qLMXBs) containing neutron stars, the origin of the thermal X-ray component may be either release of heat from the core of the neutron star, or continuing low-level accretion. In general, heat from the core should be stable on timescales $<10^4$ years, while continuing accretion may produce variations on a range of timescales. While some quiescent neutron stars (e.g. Cen X-4, Aql X-1) have shown variations in their thermal components on a range of timescales, several others, particularly those in globular clusters with no detectable nonthermal hard X-rays (fit with a powerlaw), have shown no measurable variations. Here, we constrain the spectral variations of 12 low mass X-ray binaries in 3 globular clusters over $\sim10$ years. We find no evidence of variations in 10 cases, with limits on temperature variations below 11% for the 7 qLMXBs without powerlaw components, and limits on variations below 20% for 3 other qLMXBs that do show non-thermal emission. However, in 2 qLMXBs showing powerlaw components in their spectra (NGC 6440 CX 1 & Terzan 5 CX 12) we find marginal evidence for a 10% decline in temperature, suggesting the presence of continuing low-level accretion. This work adds to the evidence that the thermal X-ray component in quiescent neutron stars without powerlaw components can be explained by heat deposited in the core during outbursts. Finally, we also investigate the correlation between hydrogen column density (N$_H$) and optical extinction (A$_V$) using our sample and current models of interstellar X-ray absorption, finding $N_H ({\rm cm}^{-2}) = (2.81\pm0.13)\times10^{21} A_V$.
|
[
"Physics Archive->astro-ph->astro-ph.HE"
] | 2015-07-14T20:00:37Z |
2211.03702
|
New counterexamples to the birational Torelli theorem for Calabi--Yau manifolds
|
We produce counterexamples to the birational Torelli theorem for Calabi-Yau manifolds in arbitrarily high dimension: this is done by exhibiting a series of non birational pairs of Calabi-Yau $(n^2-1)$-folds which, for $n \geq 2$ even, admit an isometry between their middle cohomologies. These varieties also satisfy an $\mathbb L$-equivalence relation in the Grothendieck ring of varieties, i.e. the difference of their classes annihilates a power of the class of the affine line. We state this last property for a broader class of Calabi-Yau pairs, namely all those which are realized as pushforwards of a general $(1,1)$-section on a homogeneous roof in the sense of Kanemitsu, along its two extremal contractions.
|
[
"Mathematics Archive->math.AG"
] | 2022-11-07T17:17:09Z |
1402.5122
|
Decomposition matrices are generically trivial
|
We establish a genericity property in the representation theory of a flat family of finite-dimensional algebras in the sense of Cline-Parshal-Scott. More precisely, we show that the decomposition matrices as introduced by Geck and Rouquier of an algebra which is free of finite dimension over a noetherian integral domain and which splits over the fraction field of this ring are generically trivial, i.e., they are trivial in an open neighborhood of the generic point of the spectrum of the base ring. This generalizes a classical result by Brauer in modular representation theory of finite groups. We furthermore show that this is true precisely on an open set in case all fibers of the algebra split. In this way we get a stratification of the base scheme such that decomposition maps are trivial on each stratum. Moreover, this defines a new discriminant of such algebras which generalizes Schur elements of simple modules for symmetric split semisimple algebras. We provide some extensions to the theory of decomposition maps allowing us to work without the usual normality assumption on the base ring.
|
[
"Mathematics Archive->math.RA",
"Mathematics Archive->math.RT"
] | 2014-02-20T20:14:31Z |
astro-ph/9802070
|
A Study of the Temperature gradient in Virgo/M87 with the MECS on board Beppo-SAX
|
Ground and in flight calibrations of the MECS experiment on board Beppo-SAX have demonstrated that this is currently the best X-ray imaging experiment above 3 keV. The MECS on-axis PSF has a half power radius of about 1 arcmin. Moreover due to a fortunate combination of detector and mirror PSFs the total PSF depends only weakly on the energy. Finally the degradation of the PSF with off axis angle is negligible within an off-axis angle of 10 arcminutes. Encouraged by these results we developed techniques to analyze galaxy clusters observed with Beppo-SAX. In this proceeding we quantify spectral distortions introduced by the energy dependent PSF when performing spatially resolved spectroscopy of the core of the Virgo cluster.
|
[
"Physics Archive->astro-ph"
] | 1998-02-05T17:35:28Z |
2203.00290
|
Lack of evidence for an odderon at small t
|
It is fundamental that the phase of an elastic scattering amplitude is related to its energy variation. We repeat a previous fit to proton-proton and proton-antiproton elastic scattering data from 13 to 13000 GeV, taking better account of the very high accuracy of the 13 TeV data. The conclusion remains that there is no evidence for the existence of an odderon in the small-t data
|
[
"Physics Archive->hep->hep-ex",
"Physics Archive->hep->hep-ph"
] | 2022-03-01T08:45:54Z |
hep-ph/0606232
|
Single Scale Tadpoles and O(GF mt^2 as^3) Corrections to the rho Parameter
|
We present a new set of high precision numerical values of four-loop single-scale vacuum integrals, which we subsequently use to obtain the non-singlet corrections to the rho parameter at O(GF mt^2 as^3). Our result for Delta rho is in agreement with the recent calculation [1].
|
[
"Physics Archive->hep->hep-ph"
] | 2006-06-21T15:28:47Z |
1807.04363
|
Scrambling Time and Causal Structure of the Photon Sphere of a Schwarzschild Black Hole
|
Recently, physicists have started applying quantum information theory to black holes. This led to the conjecture that black holes are the fastest scramblers of information, and that they scramble it in time order M log M, where M is the mass of the black hole in natural units. As stated above, the conjecture is not completely defined, as there are several possible definitions of scrambling times. It appears that not all papers that refer to this conjecture interpret it the same way. We consider a definition of scrambling time stronger than the one given in the paper that first proposed this conjecture [Sekino and Susskind, JHEP 0810:065 (2008)], and show that this stronger version of the conjecture appears to be incompatible with a number of other widely-believed and reasonable-sounding properties of black holes. We argue that for the scrambling time of a black hole to be this fast, either relativity is violated or non-standard physics must be occurring outside the stretched event horizon of a black hole. More specifically, either information is being transferred faster than relativity would permit, the information is not carried by the Hawking radiation and thus must be carried by unknown physics, or the Hawking radiation carries much more information than standard thermodynamics would permit.
|
[
"Physics Archive->gr-qc",
"Physics Archive->hep->hep-th",
"Physics Archive->quant-ph"
] | 2018-07-11T21:58:27Z |
funct-an/9412003
|
On dense subspaces in a class of Fr\'echet function spaces on R^n
|
When dealing with concrete problems in a function space on R^n, it is sometimes helpful to have a dense subspace consisting of functions of a particular type, adapted to the problem under consideration. We give a theorem that allows one to write down many of such subspaces in commonly occurring Fr\'echet function spaces. These subspaces are all of the form $\{pf_0 | p\in{\cal P}\}$ where $f_0$ is a fixed function and ${\cal P}$ is an algebra of functions. Classical results like the Stone-Weierstrass theorem for polynomials and the completeness of the Hermite functions are related by this theorem.
|
[
"Mathematics Archive->math.FA"
] | 1994-12-13T12:49:27Z |
1701.03117
|
Carrier driven coupling in ferromagnetic oxide heterostructures
|
Transition metal oxides are well known for their complex magnetic and electrical properties. When brought together in heterostructure geometries, they show particular promise for spintronics and colossal magnetoresistance applications. In this letter, we propose a new mechanism for the coupling between layers of itinerant ferromagnetic materials in heterostructures. The coupling is mediated by charge carriers that strive to maximally delocalize through the heterostructure to gain kinetic energy. In doing so, they force a ferromagnetic or antiferromagnetic coupling between the constituent layers. To illustrate this, we focus on heterostructures composed of SrRuO$_3$ and La$_{1-x}$A$_{x}$MnO$_3$ (A=Ca/Sr). Our mechanism is consistent with antiferromagnetic alignment that is known to occur in multilayers of SrRuO$_3$-La$_{1-x}$A$_{x}$MnO$_3$. To support our assertion, we present a minimal Kondo-lattice model which reproduces the known magnetization properties of such multilayers. In addition, we discuss a quantum well model for heterostructures and argue that the spin-dependent density of states determines the nature of the coupling. As a smoking gun signature, we propose that bilayers with the same constituents will oscillate between ferromagnetic and antiferromagnetic coupling upon tuning the relative thicknesses of the layers.
|
[
"Physics Archive->cond-mat->cond-mat.str-el"
] | 2017-01-11T19:01:53Z |
2204.02066
|
Inverse Problems Are Solvable on Real Number Signal Processing Hardware
|
Inverse problems are used to model numerous tasks in imaging sciences, in particular, they encompass any task to reconstruct data from measurements. Thus, the algorithmic solvability of inverse problems is of significant importance. The study of this question is inherently related to the underlying computing model and hardware, since the admissible operations of any implemented algorithm are defined by the computing model and the hardware. Turing machines provide the fundamental model of today's digital computers. However, it has been shown that Turing machines are incapable of solving finite dimensional inverse problems for any given accuracy. This stimulates the question of how powerful the computing model must be to enable the general solution of finite dimensional inverse problems. This paper investigates the general computation framework of Blum-Shub-Smale (BSS) machines which allows the processing and storage of arbitrary real values. Although a corresponding real world computing device does not exist at the moment, research and development towards real number computing hardware, usually referred to by the term "neuromorphic computing", has increased in recent years. In this work, we show that real number computing in the framework of BSS machines does enable the algorithmic solvability of finite dimensional inverse problems. Our results emphasize the influence of the considered computing model in questions of algorithmic solvability of inverse problems.
|
[
"Electrical Engineering and Systems Science Archive->eess.SP"
] | 2022-04-05T09:04:13Z |
2203.02495
|
Improved upper limit on degree-scale CMB B-mode polarization power from the 670 square-degree POLARBEAR survey
|
We report an improved measurement of the degree-scale cosmic microwave background $B$-mode angular-power spectrum over 670 square-degree sky area at 150 GHz with POLARBEAR. In the original analysis of the data, errors in the angle measurement of the continuously rotating half-wave plate, a polarization modulator, caused significant data loss. By introducing an angle-correction algorithm, the data volume is increased by a factor of 1.8. We report a new analysis using the larger data set. We find the measured $B$-mode spectrum is consistent with the $\Lambda$CDM model with Galactic dust foregrounds. We estimate the contamination of the foreground by cross-correlating our data and Planck 143, 217, and 353 GHz measurements, where its spectrum is modeled as a power law in angular scale and a modified blackbody in frequency. We place an upper limit on the tensor-to-scalar ratio $r$ < 0.33 at 95% confidence level after marginalizing over the foreground parameters.
|
[
"Physics Archive->astro-ph->astro-ph.CO",
"Physics Archive->astro-ph->astro-ph.IM"
] | 2022-03-04T18:50:54Z |
1708.06664
|
Emotion Detection Using Noninvasive Low Cost Sensors
|
Emotion recognition from biometrics is relevant to a wide range of application domains, including healthcare. Existing approaches usually adopt multi-electrodes sensors that could be expensive or uncomfortable to be used in real-life situations. In this study, we investigate whether we can reliably recognize high vs. low emotional valence and arousal by relying on noninvasive low cost EEG, EMG, and GSR sensors. We report the results of an empirical study involving 19 subjects. We achieve state-of-the- art classification performance for both valence and arousal even in a cross-subject classification setting, which eliminates the need for individual training and tuning of classification models.
|
[
"Computer Science Archive->cs.HC"
] | 2017-08-22T15:03:00Z |
1112.1826
|
Inverse Seesaw Mechanism in Nonsupersymmetric SO(10), Proton Lifetime, Nonunitarity Effects, and a Low-mass Z' Boson
|
Recently realization of TeV scale inverse seesaw mechanism in supersymmetric SO(10) framework has led to a number of experimentally verifiable predictions including low-mass W_R and Z' gauge bosons and nonunitarity effects. Using nonsupersymmetric SO(10) grand unified theory, we show how a TeV scale inverse seesaw mechanism for neutrino masses is implemented with a low-mass Z' boson accessible to Large Hadron Collider. We derive renormalization group equations for fermion masses and mixings in the presence of the intermediate symmetries of the model and extract the Dirac neutrino mass matrix at the TeV scale from successful GUT-scale parameterization of fermion masses. We estimate leptonic nonunitarity effects measurable at neutrino factories and lepton flavor violating decays expected to be probed in near future. While our prediction on the nonunitarity matrix element $\eta_{\mu\tau}$ for degenerate right-handed neutrinos is similar to the supersymmetric SO(10) case, we find new predictions with significantly enhanced value of its phase $\delta_{\mu\tau}\simeq 10^{-4}-10^{-2}$ when partial degeneracy among these neutrino masses is adequately taken into account by a constraint relation that emerges naturally in this approach. Other predictions on branching ratios and CP-Violating parameters are discussed. An important distinguishing characteristic as another test of the minimal model is that the threshold corrected two-loop prediction of the proton lifetime with maximum value ({\tau}_p)_{max}\simeq 10^{35} yrs. is accessible to ongoing search experiments for the decay $p\to e^+\pi^0$ in the near future. Simple model extensions with longer proton lifetime predictions are also discussed.
|
[
"Physics Archive->hep->hep-ph"
] | 2011-12-08T13:07:52Z |
1202.5001
|
On the particle paths and the stagnation points in small-amplitude deep-water waves
|
In order to obtain quite precise information about the shape of the particle paths below small-amplitude gravity waves travelling on irrotational deep water, analytic solutions of the nonlinear differential equation system describing the particle motion are provided. All these solutions are not closed curves. Some particle trajectories are peakon-like, others can be expressed with the aid of the Jacobi elliptic functions or with the aid of the hyperelliptic functions. Remarks on the stagnation points of the small-amplitude irrotational deep-water waves are also made.
|
[
"Mathematics Archive->math.MP",
"Physics Archive->math-ph"
] | 2012-02-22T18:28:20Z |
0909.1953
|
Non-unitarity effects in the minimal inverse seesaw model
|
A minimal version of the inverse seesaw model featuring only two pairs of TeV-scale singlet neutrinos is discussed from the perspective of non-standard neutrino interactions. A particular attention is paid to the non-standard patterns of flavour and CP violation emerging due to the possibly enhanced non-decoupling effects of the heavy sector and the associated non-unitarity of the effective lepton mixing matrix.
|
[
"Physics Archive->hep->hep-ph"
] | 2009-09-10T14:12:26Z |
1207.4150
|
Solving Factored MDPs with Continuous and Discrete Variables
|
Although many real-world stochastic planning problems are more naturally formulated by hybrid models with both discrete and continuous variables, current state-of-the-art methods cannot adequately address these problems. We present the first framework that can exploit problem structure for modeling and solving hybrid problems efficiently. We formulate these problems as hybrid Markov decision processes (MDPs with continuous and discrete state and action variables), which we assume can be represented in a factored way using a hybrid dynamic Bayesian network (hybrid DBN). This formulation also allows us to apply our methods to collaborative multiagent settings. We present a new linear program approximation method that exploits the structure of the hybrid MDP and lets us compute approximate value functions more efficiently. In particular, we describe a new factored discretization of continuous variables that avoids the exponential blow-up of traditional approaches. We provide theoretical bounds on the quality of such an approximation and on its scale-up potential. We support our theoretical arguments with experiments on a set of control problems with up to 28-dimensional continuous state space and 22-dimensional action space.
|
[
"Computer Science Archive->cs.AI"
] | 2012-07-11T14:57:04Z |
1304.3095
|
Knowledge and Uncertainty
|
One purpose -- quite a few thinkers would say the main purpose -- of seeking knowledge about the world is to enhance our ability to make good decisions. An item of knowledge that can make no conceivable difference with regard to anything we might do would strike many as frivolous. Whether or not we want to be philosophical pragmatists in this strong sense with regard to everything we might want to enquire about, it seems a perfectly appropriate attitude to adopt toward artificial knowledge systems. If is granted that we are ultimately concerned with decisions, then some constraints are imposed on our measures of uncertainty at the level of decision making. If our measure of uncertainty is real-valued, then it isn't hard to show that it must satisfy the classical probability axioms. For example, if an act has a real-valued utility U(E) if the event E obtains, and the same real-valued utility if the denial of E obtains, so that U(E) = U(-E), then the expected utility of that act must be U(E), and that must be the same as the uncertainty-weighted average of the returns of the act, p-U(E) + q-U('E), where p and q represent the uncertainty of E and-E respectively. But then we must have p + q = 1.
|
[
"Computer Science Archive->cs.AI"
] | 2013-03-27T19:52:50Z |
2305.18800
|
New Method for Studying the Response of the Slot Antennas in the Presence of HEMP
|
Electromagnetic Interference that is created by any methods can have an important effect on electronic and telecommunication devices. Thus, the effect of electromagnetic waves on communication systems is particularly important. Nowadays, the slot antennas are an inseparable part of many communication devices. In this paper, two methods have been introduced to evaluate the effect of interference wave on slot antennas. The first method is a classic technique based on Maxwell's equations that studied the impact of electromagnetic waves on slot antennas by using of the radiation integrals. In the second method, the slots, by using the Babinets principle are modeled with the linear antenna. Then, using linear antenna circuit and then, the equivalent circuit antennas at the receiver mode is used. Eventually, the effect of interfering waves, by calculating the voltage induced in the antenna port, is investigated. Simulation results are given to verify the usefulness of the two introduced methods. The results clearly show the reasonable outcome of the proposed methods in study of electromagnetic interference compared to the simulation results.
|
[
"Physics Archive->physics->physics.app-ph"
] | 2023-05-30T07:25:22Z |
2306.08526
|
AlbMoRe: A Corpus of Movie Reviews for Sentiment Analysis in Albanian
|
Lack of available resources such as text corpora for low-resource languages seriously hinders research on natural language processing and computational linguistics. This paper presents AlbMoRe, a corpus of 800 sentiment annotated movie reviews in Albanian. Each text is labeled as positive or negative and can be used for sentiment analysis research. Preliminary results based on traditional machine learning classifiers trained with the AlbMoRe samples are also reported. They can serve as comparison baselines for future research experiments.
|
[
"Computer Science Archive->cs.AI",
"Computer Science Archive->cs.CL",
"Computer Science Archive->cs.LG"
] | 2023-06-14T14:21:55Z |
2201.08886
|
Improved unitary uncertainty relations
|
We derive strong variance-based uncertainty relations for arbitrary two and more unitary operators by re-examining the mathematical foundation of the uncertainty relation. This is achieved by strengthening the celebrated Cauchy-Schwarz inequality using a method of brackets and convex functions. The unitary uncertainty relations outperform several strong unitary uncertainty relations, notably better than some recent best lower bounds such as [Phys. Rev. Lett. 120, 230402 (2018)] and [Phys. Rev. A. 100, 022116 (2019)].
|
[
"Mathematics Archive->math.MP",
"Physics Archive->math-ph",
"Physics Archive->quant-ph"
] | 2022-01-21T21:02:08Z |
1403.3591
|
A novel LIDAR-based Atmospheric Calibration Method for Improving the Data Analysis of MAGIC
|
A new method for analyzing the returns of the custom-made 'micro'-LIDAR system, which is operated along with the two MAGIC telescopes, allows to apply atmospheric corrections in the MAGIC data analysis chain. Such corrections make it possible to extend the effective observation time of MAGIC under adverse atmospheric conditions and reduce the systematic errors of energy and flux in the data analysis. LIDAR provides a range-resolved atmospheric backscatter profile from which the extinction of Cherenkov light from air shower events can be estimated. Knowledge of the extinction can allow to reconstruct the true image parameters, including energy and flux. Our final goal is to recover the source-intrinsic energy spectrum also for data affected by atmospheric extinction from aerosol layers, such as clouds.
|
[
"Physics Archive->astro-ph->astro-ph.IM"
] | 2014-03-14T14:43:03Z |
2204.02292
|
Parameter-Efficient Neural Reranking for Cross-Lingual and Multilingual Retrieval
|
State-of-the-art neural (re)rankers are notoriously data-hungry which -- given the lack of large-scale training data in languages other than English -- makes them rarely used in multilingual and cross-lingual retrieval settings. Current approaches therefore commonly transfer rankers trained on English data to other languages and cross-lingual setups by means of multilingual encoders: they fine-tune all parameters of pretrained massively multilingual Transformers (MMTs, e.g., multilingual BERT) on English relevance judgments, and then deploy them in the target language(s). In this work, we show that two parameter-efficient approaches to cross-lingual transfer, namely Sparse Fine-Tuning Masks (SFTMs) and Adapters, allow for a more lightweight and more effective zero-shot transfer to multilingual and cross-lingual retrieval tasks. We first train language adapters (or SFTMs) via Masked Language Modelling and then train retrieval (i.e., reranking) adapters (SFTMs) on top, while keeping all other parameters fixed. At inference, this modular design allows us to compose the ranker by applying the (re)ranking adapter (or SFTM) trained with source language data together with the language adapter (or SFTM) of a target language. We carry out a large scale evaluation on the CLEF-2003 and HC4 benchmarks and additionally, as another contribution, extend the former with queries in three new languages: Kyrgyz, Uyghur and Turkish. The proposed parameter-efficient methods outperform standard zero-shot transfer with full MMT fine-tuning, while being more modular and reducing training times. The gains are particularly pronounced for low-resource languages, where our approaches also substantially outperform the competitive machine translation-based rankers.
|
[
"Computer Science Archive->cs.CL",
"Computer Science Archive->cs.IR"
] | 2022-04-05T15:44:27Z |
1512.01440
|
On fields inspired with the polar HSV -- RGB theory of Colour
|
A three-polar, cf. T. Gregor, J. Halu\v{s}ka, Lexicographical ordering and field operations in the complex plane. Stud. Mat. 41(2014), 123--133., $HSV-RGB$ Colour space $\triangle$ was introduced and studied. It was equipped with operations of addition, subtraction, multiplication, and (partially) division. Achromatic Grey Hues form an ideal $\mathfrak{S}$. Factorizing $\triangle$ by the ideal $\mathfrak{S}$, we obtain a field $\triangle | \mathfrak{S}$. An element (i.e an individual Colour) in $\triangle | \mathfrak{S}$ is a triplet of three triangular coefficients. The set of all triangular coefficients is a subset of a semi-field of parabolic-complex functions. For the parabolic-complex number set, cf.~A. A. Harkin--J. B. Harkin, Geometry of general complex numbers. Mathematics magazine, 77(2004), 118--129.
|
[
"Mathematics Archive->math.HO"
] | 2015-11-30T12:31:47Z |
math/0305440
|
Sofic groups and direct finiteness
|
We construct an analogue of Neumann's affiliated algebras for sofic group algebras over arbitrary fields. Consequently, we settle Kaplansky's direct finiteness conjecture for sofic groups.
|
[
"Mathematics Archive->math.RA"
] | 2003-05-30T13:55:27Z |
1503.02409
|
Diffraction of entangled particles by light gratings
|
We analyze the diffraction regime of the Kapitza-Dirac effect for particles entangled in momentum. The detection patterns show two-particle interferences. In the single-mode case we identify a discontinuity in the set of joint detection probabilities, associated with the disconnected character of the space of non-separable states. For Gaussian multi-mode states we derive the diffraction patterns, providing an example of the dependence of the light-matter interaction on entanglement. When the particles are identical, we can explore the relation between exchange and entanglement effects. We find a complementary behavior between overlapping and Schmidt's number. In particular, symmetric entanglement can cancel the exchange effects.
|
[
"Physics Archive->quant-ph"
] | 2015-03-09T09:48:17Z |
2303.09142
|
Estimation of anisotropic bending rigidities and spontaneous curvatures of crescent curvature-inducing proteins from tethered-vesicle experimental data
|
The Bin/amphiphysin/Rvs (BAR) superfamily proteins have a crescent binding domain and bend biomembranes along the domain axis. However, their anisotropic bending rigidities and spontaneous curvatures have not been experimentally determined. Here, we estimated these values from the bound protein densities on tethered vesicles using a mean-field theory of anisotropic bending energy and orientation-dependent excluded volume. The dependence curves of the protein density on the membrane curvature are fitted to the experimental data for the I-BAR and N-BAR domains reported by C. Prevost et al. Nat. Commun. 6, 8529 (2015) and F.-C. Tsai et al. Soft Matter 17, 4254 (2021), respectively. For the I-BAR domain, all three density curves of different chemical potentials exhibit excellent fits with a single parameter set of anisotropic bending energy. When the classical isotropic bending energy is used instead, one of the curves can be fitted well, but the others exhibit large deviations. In contrast, for the N-BAR domain, two curves are not well-fitted simultaneously using the anisotropic model, although it is significantly improved compared to the isotropic model. This deviation likely suggests a cluster formation of the N-BAR domains.
|
[
"Physics Archive->cond-mat->cond-mat.soft",
"Physics Archive->physics->physics.bio-ph"
] | 2023-03-16T08:18:38Z |
2106.15425
|
Magnetized accretion disks around Kerr black holes with scalar hair -- Nonconstant angular momentum disks
|
We present new equilibrium solutions of stationary models of magnetized thick disks (or tori) around Kerr black holes with synchronised scalar hair. The models reported here largely extend our previous results based on constant radial distributions of the specific angular momentum along the equatorial plane. We introduce a new way to prescribe the distribution of the disk's angular momentum based on a combination of two previous proposals and compute the angular momentum distribution outside the equatorial plane by resorting to the construction of von Zeipel cylinders. We find that the effect of the scalar hair on the black hole spacetime can yield significant differences in the disk morphology and properties compared to what is found if the spacetime is purely Kerr. Some of the tori built within the most extreme, background hairy black hole spacetime of our sample exhibit the appearance of two maxima in the gravitational energy density which impacts the radial profile distributions of the disk's thermodynamical quantities. The models reported in this paper can be used as initial data for numerical evolutions with GRMHD codes to study their stability properties. Moreover, they can be employed as illuminating sources to build shadows of Kerr black holes with scalar hair which might help further constrain the no-hair hypothesis as new observational data is collected.
|
[
"Physics Archive->astro-ph->astro-ph.HE",
"Physics Archive->gr-qc"
] | 2021-06-29T13:54:13Z |
1803.04007
|
Characterizing solute hydrogen and hydrides in pure and alloyed titanium at the atomic scale
|
Ti has a high affinity for hydrogen and is a typical hydride formers. Ti-hydride are brittle phases which probably cause premature failure of Ti-alloys. Here, we used atom probe tomography and electron microscopy to investigate the hydrogen distribution in a set of specimens of commercially pure Ti, model and commercial Ti-alloys. Although likely partly introduced during specimen preparation with the focused-ion beam, we show formation of Ti-hydrides along {\alpha} grain boundaries and {\alpha}/\b{eta} phase boundaries in commercial pure Ti and {\alpha}+\b{eta} binary model alloys. No hydrides are observed in the {\alpha} phase in alloys with Al addition or quenched-in Mo supersaturation.
|
[
"Physics Archive->cond-mat->cond-mat.mtrl-sci"
] | 2018-03-11T18:40:28Z |
1806.05445
|
Comment on electron-impact excitation cross-section measurements for He-like Xenon
|
We discuss lower-than-predicted collisional-excitation cross-sections for helium-like xenon measured at an Electron Beam Ion Trap facility. In a review paper (H. Chen and P. Beiersdorfer, Can. J. Phys. 86, 55 (2008)), the authors find a significant effect due to the Breit interaction between the free and the bound electrons in the excitation process of He-like xenon. The authors state that the agreement between the measured and calculated cross-section values can only be found when the generalized Breit interaction is included in the calculations. We have performed new calculations with a Multi-Configuration Dirac-Fock code, as well as with the Penn State University suite of codes, and our conclusions are that the contribution of the Breit interaction is much lower than found in the calculations presented in the abovementioned article. In fact, our predictions are subsequently almost twice as large as the experimental values. We present these considerations in hopes of motivating new experimental investigations.
|
[
"Physics Archive->physics->physics.atom-ph"
] | 2018-06-14T10:08:32Z |
2009.11567
|
Radiative characterization of supersonic jets and shocks in a laser-plasma experiment
|
The interaction of supersonic laser-generated plasma jets with a secondary gas target was studied experimentally. The plasma parameters of the jet, and the resulting shock, were characterized using a combination of multi-frame interferometry/shadowgraphy, and X-ray diagnostics, allowing for a detailed study of their structure and evolution. The velocity was obtained with an X-ray streak camera, and filtered X-ray pinhole imaging was used to infer the electron temperature of the jet and shock. The topology of the ambient plasma density was found to have a significant effect on the jet and shock formation, as well as on their radiation characteristics. The experimental results were compared with radiation hydrodynamic simulations, thereby providing further insights into the underlying physical processes of the jet and shock formation and evolution.
|
[
"Physics Archive->physics->physics.plasm-ph"
] | 2020-09-24T09:32:27Z |
0808.1291
|
The Riesz energy of the $N$-th roots of unity: an asymptotic expansion for large $N$
|
We derive the complete asymptotic expansion in terms of powers of $N$ for the Riesz $s$-energy of $N$ equally spaced points on the unit circle as $N\to \infty$. For $s\ge -2$, such points form optimal energy $N$-point configurations with respect to the Riesz potential $1/r^{s}$, $s\neq0$, where $r$ is the Euclidean distance between points. By analytic continuation we deduce the expansion for all complex values of $s$. The Riemann zeta function plays an essential role in this asymptotic expansion.
|
[
"Mathematics Archive->math.MP",
"Physics Archive->math-ph"
] | 2008-08-08T20:15:02Z |
hep-lat/9905001
|
Pion mass and the PCAC relation in the overlap fermion formalism: Gauged Gross-Neveu model on a lattice
|
We investigate chiral properties of the overlap lattice fermion by using solvable model in two dimensions, the gauged Gross-Neveu model. In this model, the chiral symmetry is spontaneously broken in the presence of small but finite fermion mass. We calculate the quasi-Nambu-Goldstone(NG) boson mass as a function of the bare fermion mass and two parameters in the overlap formula. We find that the quasi-NG boson mass has desired properties as a result of the extended chiral symmetry found by L\"uscher. We also examine the PCAC relation and find that it is satisfied in the continuum limit. Comparison between the overlap and Wilson lattice fermions is made.
|
[
"Physics Archive->hep->hep-lat"
] | 1999-05-01T11:01:03Z |
2212.04084
|
Federated Learning for Inference at Anytime and Anywhere
|
Federated learning has been predominantly concerned with collaborative training of deep networks from scratch, and especially the many challenges that arise, such as communication cost, robustness to heterogeneous data, and support for diverse device capabilities. However, there is no unified framework that addresses all these problems together. This paper studies the challenges and opportunities of exploiting pre-trained Transformer models in FL. In particular, we propose to efficiently adapt such pre-trained models by injecting a novel attention-based adapter module at each transformer block that both modulates the forward pass and makes an early prediction. Training only the lightweight adapter by FL leads to fast and communication-efficient learning even in the presence of heterogeneous data and devices. Extensive experiments on standard FL benchmarks, including CIFAR-100, FEMNIST and SpeechCommandsv2 demonstrate that this simple framework provides fast and accurate FL while supporting heterogenous device capabilities, efficient personalization, and scalable-cost anytime inference.
|
[
"Computer Science Archive->cs.DC",
"Computer Science Archive->cs.LG"
] | 2022-12-08T05:32:33Z |
0705.2875
|
Prediction of Macrobending and Splice Losses for Photonic Crystal Fibers based on the Effective Index Method
|
An index-guiding photonic crystal fiber (PCF) with an array of air holes surrounding the silica core region has special characteristics compared to conventional single-mode fibers (SMFs). Using the effective index method and the Gaussian beam propagation theory, the macro-bending and splice losses for PCFs are investigated. The wavelength dependence of the cladding index of the PCF has been taken properly into account. We obtain the effective spot size for different configurations of PCFs, which is used for computing the splice losses. The Gaussian approximation for the fundamental modal field leads to simple closed-form expressions for the splice losses produced by transverse, longitudinal and angular offsets. Calculations of macro-bending losses are based on antenna theory for bend standard fibers.
|
[
"Physics Archive->cond-mat->cond-mat.mtrl-sci",
"Physics Archive->cond-mat->cond-mat.soft"
] | 2007-05-20T16:52:51Z |
astro-ph/9907004
|
Acquisition and analysis of adaptive optics imaging polarimetry data
|
The process of data taking, reduction and calibration of near-infrared imaging polarimetry data taken with the ESO Adaptive Optics System ADONIS is described. The ADONIS polarimetric facility is provided by a rotating wire grid polarizer. Images were taken at increments of 22.5 degrees of polarizer rotation from 0 to 180 degrees, over-sampling the polarization curve but allowing the effects of photometric variations to be assessed. Several strategies to remove the detector signature are described. The instrumental polarization was determined, by observations of stars of negligible polarization, to be 1.7% at J, H and K bands. The lack of availability of unpolarized standard stars in the IR, in particular which are not too bright as to saturate current IR detectors, is highlighted. The process of making polarization maps is described. Experiments at restoring polarimetry data, in order to reach diffraction limited polarization, are outlined, with particular reference to data on the Homunculus reflection nebula around Eta Carinae.
|
[
"Physics Archive->astro-ph"
] | 1999-07-01T07:27:44Z |
2006.06663
|
Neural Ordinary Differential Equations on Manifolds
|
Normalizing flows are a powerful technique for obtaining reparameterizable samples from complex multimodal distributions. Unfortunately current approaches fall short when the underlying space has a non trivial topology, and are only available for the most basic geometries. Recently normalizing flows in Euclidean space based on Neural ODEs show great promise, yet suffer the same limitations. Using ideas from differential geometry and geometric control theory, we describe how neural ODEs can be extended to smooth manifolds. We show how vector fields provide a general framework for parameterizing a flexible class of invertible mapping on these spaces and we illustrate how gradient based learning can be performed. As a result we define a general methodology for building normalizing flows on manifolds.
|
[
"Computer Science Archive->cs.LG",
"Statistics Archive->stat.ML"
] | 2020-06-11T17:56:34Z |
2212.10217
|
$B\to D^{(\ast)}\ell\nu$ at non-zero recoil
|
$B$ anomalies play a prominent role in Beyond the Standard Model (BSM) physics searches. In particular, the long standing tension between the inclusive and the exclusive determinations of the CKM matrix element $|V_{cb}|$ and the current tensions in the $R(D)$--$R(D^\ast)$ plane between theory and experiment have brought the $B\to D^{(\ast)}\ell\nu$ semileptonic processes to the spotlight. Existing lattice-QCD calculations of the $B\to D\ell\nu$ form factors at non-zero recoil are being complemented with very recent developments in the $B\to D^\ast\ell\nu$ channel. In this review I discuss recent progress in lattice calculations of $B\to D^{(\ast)}\ell\nu$, as well as the implications of these results for high precision determinations of $|V_{cb}|$ and the Lepton Flavor Universality (LFU) ratios $R(D^{(\ast)})$.
|
[
"Physics Archive->hep->hep-lat",
"Physics Archive->hep->hep-ph"
] | 2022-12-20T12:50:10Z |
1705.08099
|
The influence of outflow and global magnetic field on the structure and spectrum of resistive CDAFs
|
We examine the effects of a global magnetic field and outflow on radiatively inefficient accretion flow (RIAF) in the presence of magnetic resistivity. We find a self-similar solutions for the height integrated equations that govern the behavior of the flow. We use the mixing length mechanism for studying the convection parameter. We adopt a radius dependent mass accretion rate as $\dot{M}=\dot{M}_{out}{(\frac{r}{r_{out}})^{s}}$ with $s> 0$ to investigate the influence of outflow on the structure of inflow where $s$ is a constant and indication the effect of wind. Also, we have studied the radiation spectrum and temperature of CDAFs. The thermal bermsstrahlung emission as a radiation mechanism is taken into account for calculating the spectra emitted by the CDAFs. The energy that powers bremsstrahlung emission at large radii is provided by convective transport from small radii and viscous and resistivity dissipation. Our results indicate that the disc rotates slower and accretes faster, it becomes hotter and thicker for stronger wind. By increasing all component of magnetic field, the disc rotates faster and accretes slower while it becomes hotter and thicker. We show that the outflow parameter and all component of magnetic field have the same effects on the luminosity of the disc. We compare the dynamical structure of the disc in two different solutions (with and without resistivity parameter). We show that only the radial infall velocity and the surface density could changed by resistivity parameter obviously. Increasing the effect of wind increases the disc's temperature and luminosity of the disc. The effect of magnetic field is similar to the effect of wind in the disc's temperature and luminosity of the disc, but the influence of resistivity on the observational properties is not evident.
|
[
"Physics Archive->astro-ph->astro-ph.HE"
] | 2017-05-23T07:06:55Z |
hep-ph/9710529
|
On Chemical Equilibrium in Nuclear Collisions
|
The data on average hadron multiplicities in central A+A collisions measured at CERN SPS are analysed with the ideal hadron gas model. It is shown that the full chemical equilibrium version of the model fails to describe the experimental results. The agreement of the data with the off-equilibrium version allowing for partial strangeness saturation is significantly better. The freeze-out temperature of about 180 MeV seems to be independent of the system size (from S+S to Pb+Pb) and in agreement with that extracted in e+e-, pp and p{\bar p} collisions. The strangeness suppression is discussed at both hadron and valence quark level. It is found that the hadronic strangeness saturation factor gamma_S increases from about 0.45 for pp interactions to about 0.7 for central A+A collisions with no significant change from S+S to Pb+Pb collisions. The quark strangeness suppression factor lambda_S is found to be about 0.2 for elementary collisions and about 0.4 for heavy ion collisions independently of collision energy and type of colliding system
|
[
"Physics Archive->hep->hep-ph",
"Physics Archive->nucl->nucl-th"
] | 1997-10-29T17:24:05Z |
2206.09100
|
Closed-form Error Propagation on the SE_n(3) Group for Invariant Extended Kalman Filtering with Applications to VINS
|
Pose estimation is important for robotic perception, path planning, etc. Robot poses can be modeled on matrix Lie groups and are usually estimated via filter-based methods. In this paper, we establish the closed-form formula for the error propagation for the Invariant extended Kalman filter (IEKF) in the presence of random noises and apply it to vision-aided inertial navigation. We evaluate our algorithm via numerical simulations and experiments on the OPENVINS platform. Both simulations and the experiments performed on the public EuRoC MAV datasets demonstrate that our algorithm outperforms some state-of-art filter-based methods such as the quaternion-based EKF, first estimates Jacobian EKF, etc.
|
[
"Computer Science Archive->cs.RO"
] | 2022-06-18T03:39:01Z |
1401.6508
|
The Effect of Network and Infrastructural Variables on SPDY's Performance
|
HTTP is a successful Internet technology on top of which a lot of the web resides. However, limitations with its current specification, i.e. HTTP/1.1, have encouraged some to look for the next generation of HTTP. In SPDY, Google has come up with such a proposal that has growing community acceptance, especially after being adopted by the IETF HTTPbis-WG as the basis for HTTP/2.0. SPDY has the potential to greatly improve web experience with little deployment overhead. However, we still lack an understanding of its true potential in different environments. This paper seeks to resolve these issues, offering a comprehensive evaluation of SPDY's performance using extensive experiments. We identify the impact of network characteristics and website infrastructure on SPDY's potential page loading benefits, finding that these factors are decisive for SPDY and its optimal deployment strategy. Through this, we feed into the wider debate regarding HTTP/2.0, exploring the key aspects that impact the performance of this future protocol.
|
[
"Computer Science Archive->cs.NI"
] | 2014-01-25T08:58:00Z |
1311.5428
|
Mesoscopic twin boundaries in epitaxial Ni-Mn-Ga films
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Twin boundaries play an essential role in the use of magnetic shape memory alloy Ni-Mn-Ga as active material. Only if twin boundaries can be moved by an external magnetic field, high strain values of up to 10 % can be obtained. Therefore, understanding the observed twin microstructure of thin films is crucial for future application. We exemplarily present two different microstructural pattern, type X and type Y microstructure, using the example of two Ni-Mn-Ga films with similar film thickness and composition. The analysis of microstructure and structure of the thin films shows that both, type X and type Y pattern, are formed by mesoscopic 14M twin boundaries. The mesoscopic 14M twin boundaries are either tilted from the substrate surface in case of type X pattern or they are perpendicular to the surface for type Y pattern. Based on a recently proposed scenario for the nucleation of martensite in austenite, we can trace back the difference in twin boundary orientation to differently oriented martensitic nuclei.
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[
"Physics Archive->cond-mat->cond-mat.mtrl-sci"
] | 2013-11-21T14:51:51Z |
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