cometadata/datacite-rtg-text-other-reclassification-records huggingface dataset:
A Klein operator for paraparticles
Creators: name: Stoilova, N. I.
name: Van der Jeugt, J.
Publisher: name: arXiv
Year: 2021
Subjects: subject: Mathematical Physics (math-ph)
subject: High Energy Physics - Theory (hep-th)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: It has been known for a long time that there are two non-trivial possibilities for the relative commutation relations between a set of $m$ parafermions and a set of $n$ parabosons. These two choices are known as ``relative parafermion type'' and ``relative paraboson type'', and correspond to quite different underlying algebraic structures. In this short note we show how the two possibilities are related by a so-called Klein transformation.
Optical puff mediated laminar-turbulent polarization transition
Creators: name: Gao, Lei
name: Zhu, Tao
name: Wabnitz, Stefan
name: Li, Yu Jia
name: Tang, Xiao Sheng
name: Cao, Yu Long
Publisher: name: arXiv
Year: 2017
Subjects: subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: Various physical structures exhibit a fundamentally probabilistic nature over diverse scales in space and time, to the point that the demarcation line between quantum and classic laws gets blurred. Here, we characterize the probability of intermittency in the laminar-turbulence transition of a partially mode-locked fiber laser system, whose degree of coherence is deteriorated by multiple mode mixing. Two competing processes, namely the proliferation and the decay of an optical turbulent puff, determine a critical behavior for the onset of turbulence in such a nonlinear dissipative system. A new kind of optical rogue waves, polarization rogue waves, is introduced at the point of transition to polarization turbulence. The probabilistic description of the puff-mediated laminar-turbulence polarization transition provides an additional degree of freedom for our understanding of the complex physics of lasers.
Representations for the derivative at zero and finite parts of the Barnes zeta function
Creators: name: Noronha, José M. B.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Classical Analysis and ODEs (math.CA)
subject: High Energy Physics - Theory (hep-th)
subject: Mathematical Physics (math-ph)
subject: Complex Variables (math.CV)
subject: Number Theory (math.NT)
subject: FOS: Mathematics
subject: FOS: Physical sciences
subject: 33E20, 11M41, 30B40, 30E20

description: We provide new representations for the finite parts at the poles and the derivative at zero of the Barnes zeta function in any dimension in the general case. These representations are in the forms of series and limits. We also give an integral representation for the finite parts at the poles. Similar results are derived for an associated function, which we term homogeneous Barnes zeta function. Our expressions immediately yield analogous representations for the logarithm of the Barnes Gamma function, including the particular case also known as multiple Gamma function.
description: This is the Author's Original Manuscript of an article published in Integral Transforms and Special Functions (Taylor & Francis). Published article available at http://www.tandfonline.com/eprint/ME3GywdpTKcevj9jUE5t/full (There are no differences in content between the versions.)
Electron-scale reduced fluid models with gyroviscous effects
Creators: name: Passot, T.
name: Sulem, P. L.
name: Tassi, E.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Plasma Physics (physics.plasm-ph)
subject: Space Physics (physics.space-ph)
subject: FOS: Physical sciences

description: Reduced fluid models for collisionless plasmas including electron inertia and finite Larmor radius corrections are derived for scales ranging from the ion to the electron gyroradii. Based either on pressure balance or on the incompressibility of the electron fluid, they respectively capture kinetic Alfvén waves (KAWs) or whistler waves (WWs), and can provide suitable tools for reconnection and turbulence studies. Both isothermal regimes and Landau fluid closures permitting anisotropic pressure fluctuations are considered. For small values of the electron beta parameter $β_e$, a perturbative computation of the gyroviscous force valid at scales comparable to the electron inertial length is performed at order $O(β_e)$, which requires second-order contributions in a scale expansion. Comparisons with kinetic theory are performed in the linear regime. The spectrum of transverse magnetic fluctuations for strong and weak turbulence energy cascades is also phenomenologically predicted for both types of waves. In the case of moderate ion to electron temperature ratio, a new regime of KAW turbulence at scales smaller than the electron inertial length is obtained, where the magnetic energy spectrum decays like $k_\perp^{-13/3}$, thus faster than the $k_\perp^{-11/3}$ spectrum of WW turbulence.
description: 29 pages, 4 figures
Efficient algorithms for the dynamics of large and infinite classical central spin models
Creators: name: Fauseweh, Benedikt
name: Schering, Philipp
name: Hüdepohl, Jan
name: Uhrig, Götz S.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We investigate the time dependence of correlation functions in the central spin model, which describes the electron or hole spin confined in a quantum dot, interacting with a bath of nuclear spins forming the Overhauser field. For large baths, a classical description of the model yields quantitatively correct results. We develop and apply various algorithms in order to capture the long-time limit of the central spin for bath sizes from 1000 to infinitely many bath spins. Representing the Overhauser field in terms of orthogonal polynomials, we show that a carefully reduced set of differential equations is sufficient to compute the spin correlations of the full problem up to very long times, for instance up to $10^5\hbar/J_\mathrm{Q}$ where $J_\mathrm{Q}$ is the natural energy unit of the system. This technical progress renders an analysis of the model with experimentally relevant parameters possible. We benchmark the results of the algorithms with exact data for a small number of bath spins and we predict how the long-time correlations behave for different effective numbers of bath spins.
description: 13 pages, 12 figures
A unified approach to $Λ$-, $Ξ$- and $V$-type systems with one continuum
Creators: name: Sen, Surajit
name: Dey, Tushar Kanti
name: Deb, Bimalendu
Publisher: name: arXiv
Year: 2016
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: We present a systematic approach to classify the three-level-like models with two bound states coupled to a continuum. It is shown that, when one of the discrete levels of usual three-level Lambda- ($Λ$), cascade ($Ξ$) or Vee ($V$)-type systems is replaced by a continuum of states, the resulting each model can be classified into three distinct categories with nine possible configurations. We show that all these models are exactly solvable. We obtain and compare the asymmetric Fano line shapes of the spectra for all the models. Our results are important for exploring new coherent effects in a variety of physical systems involving continuum-bound coupling such as photoassociation of cold atoms, plasmonics, quantum dots, photonic crystals, electromagnetic metamaterials and so on.
description: 21 pages, 9 figures, To appear in Journal of Modern Optics
Exactly solvable lattice models for interacting electronic insulators in two dimensions
Creators: name: Wang, Qing-Rui
name: Qi, Yang
name: Fang, Chen
name: Cheng, Meng
name: Gu, Zheng-Cheng
Publisher: name: arXiv
Year: 2021
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: High Energy Physics - Theory (hep-th)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: In the past decade, tremendous efforts have been made towards understanding fermionic symmetry protected topological (FSPT) phases in interacting systems. Nevertheless, for systems with continuum symmetry, e.g., electronic insulators, it is still unclear how to construct an exactly solvable model with a finite dimensional Hilbert space in general. In this paper, we give a lattice model construction and classification for 2D interacting electronic insulators. Based on the physical picture of $\mathrm{U(1)}_f$-charge decorations, we illustrate the key idea by considering the well known 2D interacting topological insulator. Then we generalize our construction to an arbitrary 2D interacting electronic insulator with symmetry $G_f=\mathrm{U(1)}_f \rtimes_{ρ_1,ω_2} G$, where $\mathrm{U(1)}_f$ is the charge conservation symmetry and $ρ_1, ω_2$ are additional data which fully characterize the group structure of $G_f$. Finally we study more examples, including the full interacting classification of 2D crystalline topological insulators.
description: 6+11 pages, 2 figures, 3 tables
Multistep pulse compressor based on single-pass single-grating-pair main compressor
Creators: name: Du, Shuman
name: Shen, Xiong
name: Liang, Wenhai
name: Wang, Peng
name: Liu, Jun
name: Li, Ruxin
Publisher: name: arXiv
Year: 2022
Subjects: subject: Optics (physics.optics)
subject: FOS: Physical sciences

description: A multistage smoothing multistep pulse compressor (MPC) based on a single-pass single-grating-pair (SSGP) main compressor is proposed to simplify the entire petawatt (PW) compressor. Only one grating pair with relatively long distance is used to generate the same amount of spectral dispersion in the main compressor compared with a four-grating main compressor. As the SSGP induces the largest spatial dispersion, it can introduce the best beam-smoothing effect to the laser beam on the last grating. When considering the diffraction loss of only two gratings, the total compression efficiency of the SSGP main compressor is even larger than that of a four-grating main compressor. Furthermore, the spatiotemporal aberration induced by single-grating-pair can be compensated effectively by using deformable mirrors, however it is difficult or complicated to be well compensated in a four-grating compressor. Approximately 50-100 PW laser pulses can be obtained using this SSGP-based multistage smoothing MPC with a single laser beam
description: 12 pages, 8 figures
Hochschild homology of twisted crossed products and twisted graded Hecke algebras
Creators: name: Solleveld, Maarten
Publisher: name: arXiv
Year: 2022
Subjects: subject: Representation Theory (math.RT)
subject: Rings and Algebras (math.RA)
subject: FOS: Mathematics
subject: 16E40, 16S35, 20C08

description: Let A be a \C-algebra with an action of a finite group G, let $\natural$ be a 2-cocycle on $G$ and consider the twisted crossed product $A \rtimes \C [G,\natural]$. We determine the Hochschild homology of $A \rtimes \C [G,\natural]$ for two classes of algebras A: - rings of regular functions on nonsingular affine varieties, - graded Hecke algebras. The results are achieved via algebraic families of (virtual) representations and include a description of the Hochschild homology as module over the centre of $A \rtimes \C [G,\natural]$. This paper prepares for a computation of the Hochschild homology of the Hecke algebra of a reductive p-adic group.
Multi-round QAOA and advanced mixers on a trapped-ion quantum computer
Creators: name: Zhu, Yingyue
name: Zhang, Zewen
name: Sundar, Bhuvanesh
name: Green, Alaina M.
name: Alderete, C. Huerta
name: Nguyen, Nhung H.
name: Hazzard, Kaden R. A.
name: Linke, Norbert M.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Combinatorial optimization problems on graphs have broad applications in science and engineering. The Quantum Approximate Optimization Algorithm (QAOA) is a method to solve these problems on a quantum computer by applying multiple rounds of variational circuits. However, there exist several challenges limiting the real-world applications of QAOA. In this paper, we demonstrate on a trapped-ion quantum computer that QAOA results improve with the number of rounds for multiple problems on several arbitrary graphs. We also demonstrate an advanced mixing Hamiltonian that allows sampling of all optimal solutions with predetermined weights. Our results are a step towards applying quantum algorithms to real-world problems.
description: 8 pages, 5 figures
Effective Potentials Generated by Field Interaction in the Quasi-Classical Limit
Creators: name: Correggi, Michele
name: Falconi, Marco
Publisher: name: arXiv
Year: 2017
Subjects: subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: We study the {\it quasi-classical limit} of a quantum system composed of finitely many non-relativistic particles coupled to a quantized field in Nelson-type models. We prove that, as the field becomes classical and the corresponding degrees of freedom are traced out, the effective Hamiltonian of the particles converges in resolvent sense to a self-adjoint Schrödinger operator with an additional potential, depending on the state of the field. Moreover, we explicitly derive the expression of such a potential for a large class of field states and show that, for certain special sequences of states, the effective potential is trapping. In addition, we prove convergence of the ground state energy of the full system to a suitable effective variational problem involving the classical state of the field.
description: minor revision, Ann. H. Poincar\'e in press, 41 pages, pdfLaTex
Ground state energy of the low density Bose gas with three-body interactions
Creators: name: Nam, Phan Thành
name: Ricaud, Julien
name: Triay, Arnaud
Publisher: name: arXiv
Year: 2022
Subjects: subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences
subject: 35Q83, 35J10, 82B10, 82D05

description: We consider the low density Bose gas in the thermodynamic limit with a three-body interaction potential. We prove that the leading order of the ground state energy of the system is determined completely in terms of the scattering energy of the interaction potential. The corresponding result for two-body interactions was proved in seminal papers of Dyson (1957) and Lieb--Yngvason (1998).
Strong isospin breaking at production of light scalars
Creators: name: Achasov, N. N.
name: Shestakov, G. N.
Publisher: name: arXiv
Year: 2017
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Experiment (hep-ex)
subject: Nuclear Theory (nucl-th)
subject: FOS: Physical sciences

description: It is discussed breaking the isotopic symmetry as the tool of studying the mechanism production and nature of light scalar mesons.
description: 6 pages, 6 figures, N. N. Achasov's plenary talk at The 14th International Workshop on Tau Lepton Physics, 19-23 September, 2016, IHEP, Beijing, China
DESAFIOS JURÍDICOS NA ERA DAS INTELIGÊNCIAS ARTIFICIAIS: UMA ANÁLISE DA ADEQUAÇÃO DOS DIREITOS AUTORAIS E DA LEI 9.160/98 PARA CONTEÚDOS GERADOS POR FERRAMENTAS DE IA
Creators: name: Adive Cardoso FERREIRA JÚNIOR
name: Gabriel Porto CARDOSO
name: Rhaysa Nascimento da SILVA PAZ
name: Wagner Junio Moraes OLIVEIRA
Publisher: name: Zenodo
Year: 2024
Subjects: Direito autoral
IA Generativa
Proteção ao autor

description: RESUMO

 

Este artigo explora os desafios jurídicos decorrentes do uso de ferramentas de Inteligências Artificiais Generativas, como o ChatGPT, em face das normas vigentes sobre direitos autorais na legislação brasileira. À medida que essas tecnologias ganham popularidade, surgem conflitos legais e éticos significativos, principalmente no que tange à titularidade das obras criadas por tais ferramentas. Para tal, adota-se uma metodologia exploratória e indutiva, na análise da Lei de Direitos Autorais (Lei nº 9.610/98), que se apresenta inadequada às exigências impostas pelos avanços tecnológicos. A pesquisa visa determinar maneiras pelas quais a legislação atual pode ser interpretada para assegurar a proteção dos direitos dos criadores em relação às obras geradas por inteligência artificial, levando em consideração as discussões acerca da autoria e originalidade dessas produções. Os resultados apontam para a urgência de uma revisão interpretativa da lei que reconheça e preserve a criatividade e a originalidade dos autores humanos, ressaltando o papel das ferramentas de IA como auxiliares no processo criativo, sem, contudo, substituir a essencial intervenção humana. A presente análise destaca a necessidade de reformulação nos dispositivos legais acerca dos direitos autorais, com o objetivo de manter sua relevância e adaptação frente às novas tecnologias. Historicamente, observa-se que os direitos autorais têm evoluído para incorporar desafios emergentes, assim, a adaptação legislativa contínua é fundamental para a preservação de sua eficácia em um contexto tecnológico em constante transformação.
Observational appearance of Kaluza-Klein black holes
Creators: name: Mirzaev, Temurbek
name: Abdikamalov, Askar B.
name: Abdujabbarov, Ahmadjon A.
name: Ayzenberg, Dimitry
name: Ahmedov, Bobomurat
name: Bambi, Cosimo
Publisher: name: arXiv
Year: 2022
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: The optical properties of rotating black holes in Kaluza-Klein theory described by the total mass, spin, and electric and magnetic charges are investigated in detail. Using a developed general relativistic ray-tracing code to calculate the motion of photons, the numerous shadows of Kaluza-Klein black holes are generated. The properties of the black hole shadow and the light deflection angle around these black holes are also studied in order to put constraints on the parameters of Kaluza-Klein black holes using M87* shadow observations. The possibility of imposing constraints on Kaluza-Klein black holes using shadow observations is investigated. Moreover, we find that small charges (electric and magnetic) of the black hole can meet these constraints. We conclude that with the current precision of the M87* black hole shadow image observation by the EHT collaboration, the shadow observations of Kaluza-Klein black holes are indistinguishable from that of the Kerr black hole. Much better observational accuracy than the current capabilities of the EHT collaboration are required in order to place verified constraints on the parameters of modified theories of gravity in the strong field regime.
description: 13 pages, 9 figures. v2: refereed version
The completed finite period map and Galois theory of supercongruences
Creators: name: Rosen, Julian
Publisher: name: arXiv
Year: 2017
Subjects: subject: Number Theory (math.NT)
subject: FOS: Mathematics
subject: 11M32 (primary) 11A07 (secondary)

description: A period is a complex number arising as the integral of a rational function with algebraic number coefficients over a rationally-defined region. Although periods are typically transcendental numbers, there is a conjectural Galois theory of periods coming from the theory of motives. This paper formalizes an analogy between a class of periods called multiple zeta values, and congruences for rational numbers modulo prime powers (called supercongruences). We construct an analogue of the motivic period map in the setting of supercongruences, and use it to define a Galois theory of supercongruences. We describe an algorithm using our period map to find and prove supercongruences, and we provide software implementing the algorithm.
description: 24 pages. Comments are welcome. Most of the results of this paper were previously part of arXiv:1608.06864
Theoretical characterization of uncertainty in high-dimensional linear classification
Creators: name: Clarté, Lucas
name: Loureiro, Bruno
name: Krzakala, Florent
name: Zdeborová, Lenka
Publisher: name: arXiv
Year: 2022
Subjects: subject: Machine Learning (cs.LG)
subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: Machine Learning (stat.ML)
subject: FOS: Computer and information sciences
subject: FOS: Physical sciences

description: Being able to reliably assess not only the \emph{accuracy} but also the \emph{uncertainty} of models' predictions is an important endeavour in modern machine learning. Even if the model generating the data and labels is known, computing the intrinsic uncertainty after learning the model from a limited number of samples amounts to sampling the corresponding posterior probability measure. Such sampling is computationally challenging in high-dimensional problems and theoretical results on heuristic uncertainty estimators in high-dimensions are thus scarce. In this manuscript, we characterise uncertainty for learning from limited number of samples of high-dimensional Gaussian input data and labels generated by the probit model. In this setting, the Bayesian uncertainty (i.e. the posterior marginals) can be asymptotically obtained by the approximate message passing algorithm, bypassing the canonical but costly Monte Carlo sampling of the posterior. We then provide a closed-form formula for the joint statistics between the logistic classifier, the uncertainty of the statistically optimal Bayesian classifier and the ground-truth probit uncertainty. The formula allows us to investigate calibration of the logistic classifier learning from limited amount of samples. We discuss how over-confidence can be mitigated by appropriately regularising.
Polygons pulled from an adsorbing surface
Creators: name: Guttmann, AJ
name: van Rensburg, EJ Janse
name: Jensen, I
name: Whittington, SG
Publisher: name: arXiv
Year: 2017
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: FOS: Physical sciences
subject: 82B41, 82B80, 65C05

description: We consider self-avoiding lattice polygons, in the hypercubic lattice, as a model of a ring polymer adsorbed at a surface and either being desorbed by the action of a force, or pushed towards the surface. We show that, when there is no interaction with the surface, then the response of the polygon to the applied force is identical (in the thermodynamic limit) for two ways in which we apply the force. When the polygon is attracted to the surface then, when the dimension is at least 3, we have a complete characterization of the critical force--temperature curve in terms of the behaviour, (a) when there is no force, and, (b) when there is no surface interaction. For the 2-dimensional case we have upper and lower bounds on the free energy. We use both Monte Carlo and exact enumeration and series analysis methods to investigate the form of the phase diagram in two dimensions. We find evidence for the existence of a \emph{mixed phase} where the free energy depends on the strength of the interaction with the adsorbing line and on the applied force.
LDA+DMFT approach to ordering phenomena and the structural stability of correlated materials
Creators: name: Kunes, J.
name: Leonov, I.
name: Augustinsky, P.
name: Krapek, V.
name: Kollar, M.
name: Vollhardt, D.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: Materials with correlated electrons often respond very strongly to external or internal influences, leading to instabilities and states of matter with broken symmetry. This behavior can be studied theoretically either by evaluating the linear response characteristics, or by simulating the ordered phases of the materials under investigation. We developed the necessary tools within the dynamical mean-field theory (DMFT) to search for electronic instabilities in materials close to spin-state crossovers and to analyze the properties of the corresponding ordered states. This investigation, motivated by the physics of LaCoO$_3$, led to a discovery of condensation of spinful excitons in the two-orbital Hubbard model with a surprisingly rich phase diagram. The results are reviewed in the first part of the article. Electronic correlations can also be the driving force behind structural transformations of materials. To be able to investigate correlation-induced phase instabilities we developed and implemented a formalism for the computation of total energies and forces within a fully charge self-consistent combination of density functional theory and DMFT. Applications of this scheme to the study of structural instabilities of selected correlated electron materials such as Fe and FeSe are reviewed in the second part of the paper.
description: 34 pages, 11 figures
Auxiliary Cross-Modal Representation Learning with Triplet Loss Functions for Online Handwriting Recognition
Creators: name: Ott, Felix
name: Rügamer, David
name: Heublein, Lucas
name: Bischl, Bernd
name: Mutschler, Christopher
Publisher: name: arXiv
Year: 2022
Subjects: subject: Machine Learning (cs.LG)
subject: Computer Vision and Pattern Recognition (cs.CV)
subject: FOS: Computer and information sciences
subject: I.2.4
subject: 68T30, 68T35

description: Cross-modal representation learning learns a shared embedding between two or more modalities to improve performance in a given task compared to using only one of the modalities. Cross-modal representation learning from different data types -- such as images and time-series data (e.g., audio or text data) -- requires a deep metric learning loss that minimizes the distance between the modality embeddings. In this paper, we propose to use the contrastive or triplet loss, which uses positive and negative identities to create sample pairs with different labels, for cross-modal representation learning between image and time-series modalities (CMR-IS). By adapting the triplet loss for cross-modal representation learning, higher accuracy in the main (time-series classification) task can be achieved by exploiting additional information of the auxiliary (image classification) task. We present a triplet loss with a dynamic margin for single label and sequence-to-sequence classification tasks. We perform extensive evaluations on synthetic image and time-series data, and on data for offline handwriting recognition (HWR) and on online HWR from sensor-enhanced pens for classifying written words. Our experiments show an improved classification accuracy, faster convergence, and better generalizability due to an improved cross-modal representation. Furthermore, the more suitable generalizability leads to a better adaptability between writers for online HWR.
Transitions in Dynamic Point Labeling
Creators: name: Depian, Thomas
name: Li, Guangping
name: Nöllenburg, Martin
name: Wulms, Jules
Publisher: name: arXiv
Year: 2022
Subjects: subject: Computational Geometry (cs.CG)
subject: Computational Complexity (cs.CC)
subject: FOS: Computer and information sciences
subject: F.1.3; I.3.5

description: The labeling of point features on a map is a well-studied topic. In a static setting, the goal is to find a non-overlapping label placement for (a subset of) point features. In a dynamic setting, the set of point features and their corresponding labels change, and the labeling has to adapt to such changes. To aid the user in tracking these changes, we can use morphs, here called transitions, to indicate how a labeling changes. Such transitions have not gained much attention yet, and we investigate different types of transitions for labelings of points, most notably consecutive transitions and simultaneous transitions. We give (tight) bounds on the number of overlaps that can occur during these transitions. When each label has a (non-negative) weight associated to it, and each overlap imposes a penalty proportional to the weight of the overlapping labels, we show that it is NP-complete to decide whether the penalty during a simultaneous transition has weight at most $k$. Finally, in a case study, we consider geotagged Twitter data on a map, by labeling points with rectangular labels showing tweets. We developed a prototype implementation to evaluate different transition styles in practice, measuring both number of overlaps and transition duration.
Tail of the two-time height distribution for KPZ growth in one dimension
Creators: name: de Nardis, Jacopo
name: Doussal, Pierre Le
Publisher: name: arXiv
Year: 2016
Subjects: subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Disordered Systems and Neural Networks (cond-mat.dis-nn)
subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: Obtaining the exact multi-time correlations for one-dimensional growth models described by the Kardar-Parisi-Zhang (KPZ) universality class is presently an outstanding open problem. Here, we study the joint probability distribution function (JPDF) of the height of the KPZ equation with droplet initial conditions, at two different times $t_1
description: 73 pages with Appendices, 10 figures
Dilute Bose gas with three-body interaction: recent results and open questions
Creators: name: Nam, Phan Thành
name: Ricaud, Julien
name: Triay, Arnaud
Publisher: name: arXiv
Year: 2022
Subjects: subject: Mathematical Physics (math-ph)
subject: FOS: Physical sciences

description: We review our recent study on the ground state energy of dilute Bose gases with three-body interactions. The main feature of our results is the emergence of the 3D energy-critical Schrödinger equation to describe the ground state energy of a Bose-Einstein condensate, where the nonlinearity strength is determined by a zero scattering problem. Several open questions will also be discussed.
description: Contribution to the Proceedings of ICMP, 2-7 August 2021, Geneva, Switzerland. 16 pages
Reaching for the quantum limits in the simultaneous estimation of phase and phase diffusion
Creators: name: Szczykulska, Magdalena
name: Baumgratz, Tillmann
name: Datta, Animesh
Publisher: name: arXiv
Year: 2017
Subjects: subject: Quantum Physics (quant-ph)
subject: FOS: Physical sciences

description: Phase diffusion invariably accompanies all phase estimation strategies -- quantum or classical. A precise estimation of the former can often provide valuable understanding of the physics of the phase generating phenomena itself. We theoretically examine the performance of fixed-particle number probe states in the simultaneous estimation of phase and collective phase diffusion. We derive analytical quantum limits associated with the simultaneous local estimation of phase and phase diffusion within the quantum Cramer-Rao bound framework in the regimes of large and small phase diffusive noise. The former is for a general fixed-particle number state and the latter for Holland Burnett states, for which we show quantum-enhanced estimation of phase as well as phase diffusion. We next investigate the simultaneous attainability of these quantum limits using projective measurements acting on a single copy of the state in terms of a trade-off relation. In particular, we are interested how this trade-off varies as a function of the dimension of the state. We derive an analytical bound for this trade-off in the large phase diffusion regime for a particular form of the measurement, and show that the maximum of 2, set by the quantum Cramer-Rao bound, is attainable. Further, we show numerical evidence that as diffusion approaches zero, the optimal trade-off relation approaches 1 for Holland-Burnett states. These numerical results are valid in the small particle number regime and suggest that the trade-off for estimating one parameter with quantum-limited precision leads to a complete lack of precision for the other parameter as the diffusion strength approaches zero. Finally, we provide numerical results showing behaviour of the trade-off for a general value of phase diffusion when using Holland-Burnett probe states.
Refinements of the braid arrangement and two parameter Fuss-Catalan numbers
Creators: name: Deshpande, Priyavrat
name: Menon, Krishna
name: Sarkar, Writika
Publisher: name: arXiv
Year: 2022
Subjects: subject: Combinatorics (math.CO)
subject: FOS: Mathematics
subject: 52C35, 05C30

description: A hyperplane arrangement in $\mathbb{R}^n$ is a finite collection of affine hyperplanes. Counting regions of hyperplane arrangements is an active research direction in enumerative combinatorics. In this paper, we consider the arrangement $\mathcal{A}_n^{(m)}$ in $\mathbb{R}^n$ given by $\{x_i=0 \mid i \in [n]\} \cup \{x_i=a^kx_j \mid k \in [-m,m], 1\leq i1$. It turns out that this family of arrangements is closely related to the well-studied extended Catalan arrangement of type $A$. We prove that the number of regions of $\mathcal{A}_n^{(m)}$ is a certain generalization of Catalan numbers called two parameter Fuss-Catalan numbers. We then exhibit a bijection between these regions and certain decorated Dyck paths. We also compute the characteristic polynomial and give a combinatorial interpretation for its coefficients. Most of our results also generalize to sub-arrangements of $\mathcal{A}_n^{(m)}$ by relating them to deformations of the braid arrangement.
description: 18 pages, 9 figures, 1 table. Comments welcome
Massless multifold Hopf semimetals
Creators: name: Graf, Ansgar
name: Piéchon, Frédéric
Publisher: name: arXiv
Year: 2022
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Other Condensed Matter (cond-mat.other)
subject: FOS: Physical sciences

description: Three-dimensional topological semimetals exhibit linear energy band crossing points that act as monopoles of Berry curvature. Here, an alternative class of semimetals is introduced, featuring linear $N$-fold crossing points each of which acts as a source of a \emph{Berry dipole}. We construct continuum and lattice models for such \emph{massless multifold Hopf semimetals (MMHSs)} with $N=3,4,5$ bands and study nontrivial effects of a Berry dipole crossing: (i) A Landau level spectrum that is strongly tunable by the orientation of the magnetic field relative to the dipole axis. (ii) An anomalous Hall conductivity that is an odd function of the Fermi level. (iii) Weak-field dissipative magnetoconductivities that resemble the chiral anomaly, chiral magnetic and magnetochiral effects familiar from a pair of coupled Weyl nodes, but that are even functions of the Fermi level. By gapping out MMHSs, multiband Hopf insulators with Hopf numbers as high as $\mathcal{N}_\text{Hopf}=10$ are obtained, providing a fertile playground to explore delicate topology.
description: Published version
Bi-2212/1T-TaS$_2$ Van der Waals junctions: Interplay of proximity induced high-$T_c$ superconductivity and CDW order
Creators: name: Li, Ang J.
name: Zhu, Xiaochen
name: Stewart, G. R.
name: Hebard, Arthur F.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Superconductivity (cond-mat.supr-con)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Materials Science (cond-mat.mtrl-sci)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: FOS: Physical sciences

description: Understanding the coexistence, competition and/or cooperation between superconductivity and charge density waves (CDWs) in the transition metal dichalcogenides (TMDs) is an elusive goal which, when realized, promises to reveal fundamental information on this important class of materials. Here, we use four-terminal current-voltage measurements to study the Van der Waals interface between freshly exfoliated flakes of the high-$T_{c}$ superconductor, Bi-2212, and the CDW-dominated TMD layered material, 1T-TaS$_{2}$. For highly transparent barriers, there is a pronounced Andreev reflection feature providing evidence for proximity-induced high-$T_{c}$ superconductivity in 1T-TaS$_{2}$ with a surprisingly large energy gap ($\sim 20\thinspace $meV) equal to half that of intrinsic Bi-2212 ($\sim 40\thinspace $meV). Our systematic study using conductance spectroscopy of junctions with different transparencies also reveals the presence of two separate boson modes, each associated with a "dip-hump" structure. We infer that the proximity-induced high-$T_c$ superconductivity in the 1T-TaS$_2$ is driven by coupling to the metastable metallic phase coexisting within the Mott commensurate CDW (CCDW) phase and associated with a concomitant change of the CCDW order parameter in the interfacial region.
description: 27 pages, 11 figures
The Einstein-Boltzmann equations revisited
Creators: name: Nadkarni-Ghosh, Sharvari
name: Refregier, Alexandre
Publisher: name: arXiv
Year: 2016
Subjects: subject: General Relativity and Quantum Cosmology (gr-qc)
subject: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
subject: FOS: Physical sciences

description: The linear Einstein-Boltzmann equations describe the evolution of perturbations in the universe and its numerical solutions play a central role in cosmology. We revisit this system of differential equations and present a detailed investigation of its mathematical properties. For this purpose, we focus on a simplified set of equations aimed at describing the broad features of the matter power spectrum. We first perform an eigenvalue analysis and study the onset of oscillations in the system signaled by the transition from real to complex eigenvalues. We then provide a stability criterion of different numerical schemes for this linear system and estimate the associated step-size. We elucidate the stiffness property of the Einstein-Boltzmann system and show how it can be characterized in terms of the eigenvalues. While the parameters of the system are time dependent making it non-autonomous, we define an adiabatic regime where the parameters vary slowly enough for the system to be quasi-autonomous. We summarize the different regimes of the system for these different criteria as function of wave number $k$ and scale factor $a$. We also provide a compendium of analytic solutions for all perturbation variables in 6 limits on the $k$-$a$ plane and express them explicitly in terms of initial conditions. These results are aimed to help the further development and testing of numerical cosmological Boltzmann solvers.
description: 41 pages (21 text + appendices), 19 figures and 2 tables; accepted in MNRAS
Growth factors of random butterfly matrices and the stability of avoiding pivoting
Creators: name: Peca-Medlin, John
name: Trogdon, Thomas
Publisher: name: arXiv
Year: 2022
Subjects: subject: Numerical Analysis (math.NA)
subject: Probability (math.PR)
subject: FOS: Mathematics
subject: 60B20, 15A23, 65F99

description: Random butterfly matrices were introduced by Parker in 1995 to remove the need for pivoting when using Gaussian elimination. The growing applications of butterfly matrices have often eclipsed the mathematical understanding of how or why butterfly matrices are able to accomplish these given tasks. To help begin to close this gap using theoretical and numerical approaches, we explore the impact on the growth factor of preconditioning a linear system by butterfly matrices. These results are compared to other common methods found in randomized numerical linear algebra. In these experiments, we show preconditioning using butterfly matrices has a more significant dampening impact on large growth factors than other common preconditioners and a smaller increase to minimal growth factor systems. Moreover, we are able to determine the full distribution of the growth factors for a subclass of random butterfly matrices. Previous results by Trefethen and Schreiber relating to the distribution of random growth factors were limited to empirical estimates of the first moment for Ginibre matrices.
Does Greed Help a Forager Survive?
Creators: name: Bhat, U.
name: Redner, S.
name: Benichou, O.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Populations and Evolution (q-bio.PE)
subject: Statistical Mechanics (cond-mat.stat-mech)
subject: Biological Physics (physics.bio-ph)
subject: FOS: Biological sciences
subject: FOS: Physical sciences

description: We investigate the role of greed on the lifetime of a random-walking forager on an initially resource-rich lattice. Whenever the forager lands on a food-containing site, all the food there is eaten and the forager can hop $\mathcal{S}$ more steps without food before starving. Upon reaching an empty site, the forager comes one time unit closer to starvation. The forager is also greedy---given a choice to move to an empty or to a food-containing site in its local neighborhood, the forager moves preferentially towards food. Surprisingly, the forager lifetime varies non-monotonically with greed, with different senses of the non-monotonicity in one and two dimensions. Also unexpectedly, the forager lifetime in one dimension has a huge peak for very negative greed.
description: 5 pages, 4 figures, 2-column revtex format. Version 2 is expanded in response to referee comments. For publication in PRE
Covariant Response Theory and the Boost Transform of the Dielectric Tensor
Creators: name: Starke, R.
name: Schober, G. A. H.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Classical Physics (physics.class-ph)
subject: General Relativity and Quantum Cosmology (gr-qc)
subject: FOS: Physical sciences

description: After a short critique of the Minkowski formulae for the electromagnetic constitutive laws in moving media, we argue that in actual fact the problem of Lorentz-covariant electromagnetic response theory is automatically solved within the framework of modern microscopic electrodynamics of materials. As an illustration, we first rederive the well-known relativistic transformation behavior of the microscopic conductivity tensor. Thereafter, we deduce from first principles the transformation law of the wavevector- and frequency-dependent dielectric tensor under Lorentz boost transformations.
description: consistent with published version in Int. J. Mod. Phys. D (2017)
Duality and Universal Transport in a Mixed-Dimension Electrodynamics
Creators: name: Hsiao, Wei-Han
name: Son, Dam Thanh
Publisher: name: arXiv
Year: 2017
Subjects: subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: Strongly Correlated Electrons (cond-mat.str-el)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We consider a theory of a two-component Dirac fermion localized on a (2+1) dimensional brane coupled to a (3+1) dimensional bulk. Using the fermionic particle-vortex duality, we show that the theory has a strong-weak duality that maps the coupling $e$ to $\tilde e=(8π)/e$. We explore the theory at $e^2=8π$ where it is self-dual. The electrical conductivity of the theory is a constant independent of frequency. When the system is at finite density and magnetic field at filling factor $ν=\frac12$, the longitudinal and Hall conductivity satisfies a semicircle law, and the ratio of the longitudinal and Hall thermal electric coefficients is completely determined by the Hall angle. The thermal Hall conductivity is directly related to the thermal electric coefficients.
description: 6 pages
A Derivation of Nesterov's Accelerated Gradient Algorithm from Optimal Control Theory
Creators: name: Ross, I. M.
Publisher: name: arXiv
Year: 2022
Subjects: subject: Optimization and Control (math.OC)
subject: Machine Learning (cs.LG)
subject: FOS: Mathematics
subject: FOS: Computer and information sciences
subject: G.1.6; I.2.8
subject: 90C25, 49K15, 93D05, 68T07

description: Nesterov's accelerated gradient algorithm is derived from first principles. The first principles are founded on the recently-developed optimal control theory for optimization. This theory frames an optimization problem as an optimal control problem whose trajectories generate various continuous-time algorithms. The algorithmic trajectories satisfy the necessary conditions for optimal control. The necessary conditions produce a controllable dynamical system for accelerated optimization. Stabilizing this system via a quadratic control Lyapunov function generates an ordinary differential equation. An Euler discretization of the resulting differential equation produces Nesterov's algorithm. In this context, this result solves the purported mystery surrounding the algorithm.
description: 7 pages. arXiv admin note: text overlap with arXiv:1902.09004
A Clockwork WIMP
Creators: name: Hambye, Thomas
name: Teresi, Daniele
name: Tytgat, Michel H. G.
Publisher: name: arXiv
Year: 2016
Subjects: subject: High Energy Physics - Phenomenology (hep-ph)
subject: High Energy Physics - Theory (hep-th)
subject: FOS: Physical sciences

description: We embed a thermal dark matter (DM) candidate within the clockwork framework. This mechanism allows to stabilize the DM particle over cosmological time because it suppresses its decay into Standard Model (SM) particles. At the same time, pair annihilations are unsuppressed, so that the relic density is set by the usual freeze-out of the DM particle from the thermal bath. The slow decay of the DM candidate is induced by "clockwork" particles that can be quite light (rather than at some GUT or Planck scale) and could be searched for at current or future colliders. According to the scenario considered, the very same particles also mediate the annihilation process, thus providing a connection between DM annihilation and DM decay, and fixing the mass scale of the clockwork states, otherwise unconstrained, to be in the TeV range or lighter. We then show how this setup can minimally emerge from the deconstruction of an extra dimension in flat spacetime. Finally, we argue that the clockwork mechanism that we consider could induce Majorana neutrino masses, with a seesaw scale of order TeV or less and Yukawa couplings of order unity.
description: 10 pages, 3 figures. Published version
Modelling and characterization of a pneumatically actuated peristaltic micropump
Creators: name: Gerasimenko, T. N.
name: Kindeeva, O. V.
name: Petrov, V. A.
name: Khaustov, A. I.
name: Trushkin, E. V.
Publisher: name: arXiv
Year: 2017
Subjects: subject: Fluid Dynamics (physics.flu-dyn)
subject: FOS: Physical sciences

description: There is an emerging class of microfluidic bioreactors which possess long-term, closed circuit perfusion under sterile conditions with in vivo-like flow parameters. Integrated into microfluidics, peristaltic-like pneumatically actuated displacement micropumps are able to meet these requirements. We present both a theoretical and experimental characterization of such pumps. In order to examine volume flow rate, we have developed a mathemati- cal model describing membrane motion under external pressure. The viscoelasticity of the membrane and hydrodynamic resistance of the microfluidic channel have been taken into account. Unlike other models, the developed model includes only the physical parameters of the pump and allows the estimation of their impact on the resulting flow. The model has been validated experimentally.
Correct Brillouin zone and electronic structure of BiPd
Creators: name: Yaresko, Alexander
name: Schnyder, Andreas P.
name: Benia, Hadj M.
name: Yim, Chi-Ming
name: Levy, Giorgio
name: Damascelli, Andrea
name: Ast, Christian R.
name: Peets, Darren C.
name: Wahl, Peter
Publisher: name: arXiv
Year: 2017
Subjects: subject: Materials Science (cond-mat.mtrl-sci)
subject: Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
subject: FOS: Physical sciences

description: A promising route to the realization of Majorana fermions is in non-centrosymmetric superconductors, in which spin-orbit-coupling lifts the spin degeneracy of both bulk and surface bands. A detailed assessment of the electronic structure is critical to evaluate their suitability for this through establishing the topological properties of the electronic structure. This requires correct identification of the time-reversal-invariant momenta. One such material is BiPd, a recently rediscovered non-centrosymmetric superconductor which can be grown in large, high-quality single crystals and has been studied by several groups using angular resolved photoemission to establish its surface electronic structure. Many of the published electronic structure studies on this material are based on a reciprocal unit cell which is not the actual Brillouin zone of the material. We show here the consequences of this for the electronic structures and show how the inferred topological nature of the material is affected.
description: Originally a comment on 1505.03466/1610.03431 and 1609.08947. 4 pages plus an appendix with literature crystal structure refinements