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Functional relations for elliptic polylogarithms J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200601
Johannes Broedel and André KaderliNumerous examples of functional relations for multiple polylogarithms are known. For elliptic polylogarithms, however, tools for the exploration of functional relations are available, but only very few relations are identified. Starting from an approach of Zagier and Gangl, which in turn is based on considerations about an elliptic version of the Bloch group, we explore functional relations between

A Q operator for open spin chains I. Baxter’s TQ relation J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200531
Bart Vlaar and Robert WestonWe construct a Q operator for the open XXZ Heisenberg quantum spin chain with diagonal boundary conditions and give a rigorous derivation of Baxter’s TQ relation. Key roles in the theory are played by a particular infinitedimensional solution of the reflection equation and by short exact sequences of intertwiners of the standard Borel subalgebras of ##IMG## [http://ej.iop.org/images/17518121/53

Uncertainty and tradeoffs in quantum multiparameter estimation J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200531
Ilya Kull, Philippe Allard Guérin and Frank VerstraeteUncertainty relations in quantum mechanics express bounds on our ability to simultaneously obtain knowledge about expectation values of noncommuting observables of a quantum system. They quantify tradeoffs in accuracy between complementary pieces of information about the system. In quantum multiparameter estimation, such tradeoffs occur for the precision achievable for different parameters characterizing

Effective methods for constructing extreme quantum observables J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200528
E Haapasalo and JP PellonpääWe study extreme points of the set of finiteoutcome positiveoperatorvalued measures (POVMs) on finitedimensional Hilbert spaces and particularly the possible ranks of the effects of an extreme POVM. We give results discussing ways of deducing new rank combinations of extreme POVMs from rank combinations of known extreme POVMs and, using these results, show ways to characterize rank combinations

Lindblad approximation and spin relaxation in quantum electrodynamics J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200528
L Amour and J NourrigatThis article is concerned with the time evolution of spin observables for generalized spin boson models. This applies in particular to a model of nuclear magnetic resonance, namely a ##IMG## [http://ej.iop.org/images/17518121/53/24/245204/aab8e04ieqn1.gif] {$\frac{1}{2}$} spin particle in a constant external magnetic field and in interaction with the quantized electromagnetic field (photons). We

Computing defects associated to bounded domain wall structures: the ##IMG## [http://ej.iop.org/images/17518121/53/23/235206/toc_aab7d60ieqn1.gif] {$\mathbb{Z}/p\mathbb{Z}$} case J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200528
Jacob C Bridgeman and Daniel BarterWe discuss domain walls and defects in topological phases occurring as the Drinfeld center of some fusion category. Domain walls between such phases correspond to bimodules between the fusion categories. Point defects correspond to functors between the bimodules. A domain wall structure consists of a planar graph with faces labeled by fusion categories. Edges are labeled by bimodules. When the vertices

An exact solution method for the enumeration of connected Feynman diagrams J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200528
E R Castro and I RoditiWe completely generalize previous results related to the counting of connected Feynman diagrams. We use a generating function approach, which encodes the Wick contraction combinatorics of the respective connected diagrams. Exact solutions are found for an arbitrary number of external legs, and a general algorithm is implemented for this calculus. From these solutions, we calculate many asymptotics

Macroscopic approach to Nqudit systems J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200528
C Muñoz, I Sainz and A B KlimovWe develop a general scheme for an analysis of macroscopic N qudit systems which includes: (a) a scheme to organize the information obtained from collective measurements in the form of distribution functions in a discrete lowdimensional space; (b) a set of collective operators appropriate for the characterization of N qudit states; (c) two collective tomographic protocols both for general and fully

Lattice models, deformed Virasoro algebra and reduction equation J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200528
Michael Lashkevich, Yaroslav Pugai, Jun’ichi Shiraishi and Yohei TutiyaWe study the fused currents of the deformed Virasoro algebra. By constructing a homotopy operator we show that for special values of the parameter of the algebra fused currents pairwise coincide on the cohomologies of the Felder resolution. Within the algebraic approach to lattice models these currents are known to describe neutral excitations of the solidonsolid (SOS) models in the transfermatrix

Duality between hydrogen atom and oscillator systems via hidden SO( d ,2) symmetry and 2Tphysics J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200526
Itzhak Bars and Jonathan L RosnerThe relation between motion in −1/ r and r 2 potentials, known since Newton, can be demonstrated by the substitution r → r 2 in the classical/quantum radial equations of the Kepler/Hydrogen problems versus the harmonic oscillator. This suggests a dualitytype relationship between these systems. However, when both radial and angular components of these systems are included the possibility of a true

Expansions in the delay of quasiperiodic solutions for state dependent delay equations J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200525
Alfonso Casal, Livia Corsi and Rafael de la LlaveWe consider several models of state dependent delay differential equations (SDDEs), in which the delay is affected by a small parameter. This is a very singular perturbation since the nature of the equation changes. Under some conditions, we construct formal power series, which solve the SDDEs order by order. These series are quasiperiodic functions of time. This is very similar to the Lindstedt procedure

Proof of Sarkar–Kumar’s conjectures on average entanglement entropies over the Bures–Hall ensemble J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200525
Lu WeiSarkar and Kumar recently conjectured (2019 J. Phys. A: Math. Theor. 52 295203) that for a bipartite system of Hilbert dimension mn , the mean values of quantum purity and von Neumann entropy of a subsystem of dimension m ⩽ n over the Bures–Hall measure are given by ##IMG## [http://ej.iop.org/images/17518121/53/23/235203/aab8d07ieqn1.gif] {$\frac{2n\left(2n\,+\,m\right)\,\,{m}^{2}\,+\,1}{2n\left(2mn\

Energy and momentum conservation in the Euler–Poincaré formulation of local Vlasov–Maxwelltype systems J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200525
Eero Hirvijoki, Joshua W Burby, David Pfefferlé and Alain J BrizardThe action principle by Low (1958 Proc. R. Soc. Lond. A 248 282–7) for the classic Vlasov–Maxwell system contains a mix of Eulerian and Lagrangian variables. This renders the Noether analysis of reparametrization symmetries inconvenient, especially since the wellknown energy and momentumconservation laws for the system are expressed in terms of Eulerian variables only. While an Euler–Poincaré formulation

Functional equations for regularized zetafunctions and diffusion processes J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200525
A Saldivar, N F Svaiter and C A D ZarroWe discuss modifications in the integral representation of the Riemann zetafunction that lead to generalizations of the Riemann functional equation that preserves the symmetry s → (1 − s ) in the critical strip. By modifying one integral representation of the zetafunction with a cutoff that does exhibit the symmetry x ↦ 1/ x , we obtain a generalized functional equation involving Bessel functions

The Godbillon–Vey invariant as a restricted Casimir of threedimensional ideal fluids J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200525
Thomas MachonWe show the Godbillon–Vey invariant arises as a ‘restricted Casimir’ invariant for threedimensional ideal fluids associated to a foliation. We compare to a finitedimensional system, the rattleback, where analogous phenomena occur.

Revealing roaming on the double Morse potential energy surface with Lagrangian descriptors J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200525
Francisco Gonzalez Montoya and Stephen WigginsIn this paper, we analyse the phase space structure of the roaming dynamics in a 2 degree of freedom potential energy surface consisting of two identical planar Morse potentials separated by a distance. This potential energy surface was previously studied in Carpenter B K et al (2018 Regul. Chaotic Dyn. 23 60–79), and it has two potential wells surrounded by an unbounded flat region containing no critical

Equilibrium properties and decoherence of an open harmonic oscillator J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200525
Janos PolonyiThe equilibrium properties of an open harmonic oscillator are considered in three steps: first the creation and destruction operators are generalized for open dynamics and the creation operator is used to construct coherent states. The second step consists of the introduction of the Heisenberg representation where the dynamical decoherence is identified. Finally it is pointed out that the quantum fluctuations

Meanfield inference methods for neural networks J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200519
Marylou GabriéMachine learning algorithms relying on deep neural networks recently allowed a great leap forward in artificial intelligence. Despite the popularity of their applications, the efficiency of these algorithms remains largely unexplained from a theoretical point of view. The mathematical description of learning problems involves very large collections of interacting random variables, difficult to handle

Analysis of interactions in totally asymmetric exclusion process with sitedependent hopping rates: theory and simulations J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200518
Akriti Jindal, Tripti Midha and Arvind Kumar GuptaBiological molecular motors are special enzymes that support biological processes such as intracellular transport, vesicle locomotion, RNA translation and many more. Experimental works suggest that the motor proteins interact among each other and moreover they experience a push by other motors during the intracellular transport. To incorporate these dynamics, we consider a variant of open onedimensional

Symmetries of ##IMG## [http://ej.iop.org/images/17518121/53/23/235201/toc_aab8b36ieqn1.gif] {${\mathbb{Z}}_{N}$} graded discrete integrable systems J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200518
Allan P Fordy and Pavlos XenitidisWe recently introduced a class of ##IMG## [http://ej.iop.org/images/17518121/53/23/235201/aab8b36ieqn2.gif] {${\mathbb{Z}}_{N}$} graded discrete Lax pairs and studied the associated discrete integrable systems (lattice equations). We discuss differential–difference equations which then we interpret as symmetries of the discrete systems. In particular, we present nonlocal symmetries which are associated

Superoscillations for monochromatic standing waves J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200517
M V BerryFor complex scalar waves, a convenient measure of the local oscillations and (‘faster than Fourier’) superoscillations is the phase gradient vector: the local wavevector, or weak value of the momentum operator. This vanishes for standing waves, described by real functions ψ ( r ); for such waves, an alternative descriptor of oscillations is the local weak value of the square of one of the momentum

Generic triangular solutions of the reflection equation: ##IMG## [http://ej.iop.org/images/17518121/53/22/225202/toc_aab8853ieqn1.gif] {${U}_{q}\left(\hat{s{l}_{2}}\right)$} case J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200517
Zengo TsuboiWe consider intertwining relations of the triangular q Onsager algebra, and obtain generic triangular boundary K operators in terms of the Borel subalgebras of U q ( sl 2 ). These K operators solve the reflection equation.

Chebyshev polynomial expansion of twodimensional Landau–Fermi liquid parameters J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200517
Joshuah T Heath, Matthew P Gochan and Kevin S BedellWe study the intrinsic effects of dimensional reduction on the transport equation of a perfectly twodimensional Landau–Fermi liquid. By employing the orthogonality condition on the 2D analog of the Fourier–Legendre expansion, we find that the equilibrium and nonequilibrium properties of the fermionic system differ from its threedimensional counterpart, with the latter changing drastically. Specifically

Geometric aspects of the ODE/IM correspondence J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200514
Patrick Dorey, Clare Dunning, Stefano Negro and Roberto TateoThis review describes a link between Lax operators, embedded surfaces and thermodynamic Bethe ansatz equations for integrable quantum field theories. This surprising connection between classical and quantum models is undoubtedly one of the most striking discoveries that emerged from the offcritical generalisation of the ODE/IM correspondence, which initially involved only conformal invariant quantum

On the oddness of percolation J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200513
C AppertRolland and H J HilhorstRecently Mertens and Moore (2019 Phys . Rev . Lett . 123 230605) showed that site percolation ‘is odd’. By this they mean that on an M × N square lattice the number of distinct site configurations that allow for vertical percolation is odd. We report here an alternative proof, based on recursive use of geometric symmetry, for both free and periodic boundary conditions.

Moderate deviations for diffusion in time dependent random media J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200511
Guillaume Barraquand and Pierre Le DoussalThe position x ( t ) of a particle diffusing in a onedimensional uncorrelated and time dependent random medium is simply Gaussian distributed in the typical direction, i.e. along the ray x = v 0 t , where v 0 is the average drift. However, it has been found that it exhibits at large time sample to sample fluctuations characteristic of the Kardar–Parisi–Zhang (KPZ) universality class when observed

Stationary state degeneracy of open quantum systems with nonabelian symmetries J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200511
Zh Zhang, J Tindall, J MurPetit, D Jaksch and B BučaWe study the null space degeneracy of open quantum systems with multiple nonabelian, strong symmetries. By decomposing the Hilbert space representation of these symmetries into an irreducible representation involving the direct sum of multiple, commuting, invariant subspaces we derive a tight lower bound for the stationary state degeneracy. We apply these results within the context of open quantum

Minimum measurement time: lower bound on the frequency cutoff for collapse models J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200511
Stephen L Adler, Angelo Bassi and Luca FerialdiThe CSL model predicts a progressive breakdown of the quantum superposition principle, with a noise randomly driving the state of the system towards a localized one, thus accounting for the emergence of a classical world within a quantum framework. In the original model the noise is supposed to be white, but since white noises do not exist in nature, it becomes relevant to identify some of its spectral

Extremal elements of a sublattice of the majorization lattice and approximate majorization J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200511
C Massri, G Bellomo, F Holik and G M BosykGiven a probability vector x with its components sorted in nonincreasing order, we consider the closed ball ##IMG## [http://ej.iop.org/images/17518121/53/21/215305/aab8674ieqn1.gif] {${\mathcal{B}}_{{\epsilon}}^{p}\left(x\right)$} with p ⩾ 1 formed by the probability vectors whose ℓ p norm distance to the center x is less than or equal to a radius ϵ . Here, we provide an ordertheoretic characterization

Ground state wave functions for the quantum Hall effect on a sphere and the Atiyah–Singer index theorem J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200511
Brian P Dolan and Aonghus HunterMcCabeThe quantum Hall effect is studied in a spherical geometry using the Dirac operator for noninteracting fermions in a background magnetic field, which is supplied by a Wu–Yang magnetic monopole at the center of the sphere. Wave functions are crosssection of a nontrivial U (1) bundle, the zero point energy then vanishes and no perturbations can lower the energy. The Atiyah–Singer index theorem constrains

Learning quantum models from quantum or classical data J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200511
H J KappenIn this paper, we address the problem of how to represent a classical data distribution in a quantum system. The proposed method is to learn the quantum Hamiltonian, that is such that its ground state approximates the given classical distribution. We review previous work on the quantum Boltzmann machine (QBM) (Kieferová M and Nathan W 2017 Phys. Rev. A 96 062327, Amin M H et al 2018 Phys. Rev. X 8

Critical exponent for the Lyapunov exponent and phase transitions—the generalized Hamiltonian meanfield model J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200510
M F P Silva Jr, T M Rocha Filho and Y ElskensWe compute semianalytic and numerical estimates for the largest Lyapunov exponent in a manyparticle system with longrange interactions, extending previous results for the Hamiltonian mean field model with a cosine potential. Our results evidence a critical exponent associated to a power law decay of the largest Lyapunov exponent close to secondorder phase transitions, close to the same value as

Equivalence classes of coherent projectors in a Hilbert space with prime dimension: Q functions and their Gini index J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200510
A VourdasCoherent subspaces spanned by a finite number of coherent states are introduced, in a quantum system with Hilbert space that has odd prime dimension d . The set of all coherent subspaces is partitioned into equivalence classes, with d 2 subspaces in each class. The corresponding coherent projectors within an equivalence class, have the ‘closure under displacements property’ and also resolve the identity

Time evolution of entanglement negativity across a defect J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200504
Matthias Gruber and Viktor EislerWe consider a quench in a freefermion chain by joining two homogeneous halfchains via a defect. The time evolution of the entanglement negativity is studied between adjacent segments surrounding the defect. In case of equal initial fillings, the negativity grows logarithmically in time and essentially equals onehalf of the Rényi mutual information with index α = 1/2 in the limit of large segments

Variational formulation of compressible hydrodynamics in curved spacetime and symmetry of stress tensor J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200504
T Koide and T KodamaHydrodynamics of the nonrelativistic compressible fluid in the curved spacetime is derived using the generalized framework of the stochastic variational method (SVM) for continuum medium. The fluidstress tensor of the resultant equation becomes asymmetric for the exchange of the indices, different from the standard Euclidean one. Its incompressible limit suggests that the viscous term should be represented

The Whitham approach to the c → 0 limit of the Lieb–Liniger model and generalized hydrodynamics J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200503
Eldad BettelheimThe Whitham approach is a wellstudied method to describe nonlinear integrable systems. Although approximate in nature, its results may predict rather accurately the time evolution of such systems in many situations given initial conditions. A similarly powerful approach has recently emerged that is applicable to quantum integrable systems, namely the generalized hydrodynamics approach. This paper

Weak selfsimilarity of the Mittag–Leffler relaxation function J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200503
Gerald R Kneller and Melek SaouessiThe Mittag–Leffler (ML) relaxation function, E α (− t α ) (0 < α ⩽ 1), describes multiscale relaxation processes with a broad range of relaxation rates, where α = 1 corresponds to exponential relaxation. For 0 < α < 1 it decays asymptotically ∼ t − α and is thus asymptotically selfsimilar, i.e. form invariant under a scale transform t → μt . In the language of asymptotic analysis, such functions are

Quantum simulation of quantum relativistic diffusion via quantum walks J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200430
Pablo Arnault, Adrian Macquet, Andreu AnglésCastillo, Iván MárquezMartín, Vicente PinaCanelles, Armando Pérez, Giuseppe Di Molfetta, Pablo Arrighi and Fabrice DebbaschTwo models are first presented, of a onedimensional discretetime quantum walk (DTQW) with temporal noise on the internal degree of freedom (i.e., the coin): (i) a model with both a coinflip and a phaseflip channel, and (ii) a model with random coin unitaries. It is then shown that both these models admit a common limit in the spacetime continuum, namely, a Lindblad equation with Diracfermion Hamiltonian

A simple observation and its unexpected consequences J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200430
G VenezianoThis is the story of a simple observation made by Peter (and independently by Haim Harari) more than half a century ago and whose unexpectedly rich consequences have kept bugging my mind, on and off, till these days.

On Christol’s conjecture J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200430
Y Abdelaziz, C Koutschan and JM MaillardWe show that the unresolved examples of Christol’s conjecture ##IMG## [http://ej.iop.org/images/17518121/53/20/205201/aab82dcieqn3.gif] {${\;}_{3}{F}_{2}\left(\left[2/9,5/9,8/9\right],\left[2/3,1\right],x\right)$} and ##IMG## [http://ej.iop.org/images/17518121/53/20/205201/aab82dcieqn4.gif] {${\;}_{3}{F}_{2}\left(\left[1/9,4/9,7/9\right],\left[1/3,1\right],x\right)$} , are indeed diagonals of rational

Bulkboundary correspondence for topological insulators with quantized magnetoelectric effect J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200430
Bryan Leung and Emil ProdanWe study bulkboundary correspondences and related surface phenomenastabilized by the second Chern number in threedimensional insulators driven in adiabatic cycles. Magnetic fields and disorder effects are incorporated in our analysis using operator algebraic methods. We use the connecting maps between the K theories of bulk and boundary algebras as engines for the bulkboundary correspondences.

Mass gaps and braneworlds J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200429
K S StelleRemembering the foundational contributions of Peter Freund to supergravity, and especially to the problems of dimensional compactification, reduction is considered with a noncompact space transverse to the lower dimensional theory. The known problem of a continuum of Kaluza–Klein states is avoided here by the occurrence of a mass gap between a single normalizable zeroeigenvalue transverse wavefunction

Fast state tomography with optimal error bounds J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200429
M Guţă, J Kahn, R Kueng and J A TroppProjected least squares is an intuitive and numerically cheap technique for quantum state tomography: compute the leastsquares estimator and project it onto the space of states. The main result of this paper equips this point estimator with rigorous, nonasymptotic convergence guarantees expressed in terms of the trace distance. The estimator’s sample complexity is comparable to the strongest convergence

Preface: new trends in firstpassage methods and applications in the life sciences and engineering J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200428
Denis S Grebenkov, David Holcman and Ralf MetzlerDescription unavailable

The early days of string theory and an N pion extension of the Lovelace–Shapiro model J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200428
Paolo Di VecchiaWe discuss the attempts made at the end of the sixties and at the beginning of the seventies in order to get a consistent N point amplitude involving the lightest hadrons, such as the pion, that then brought to string theory containing massless gluons and gravitons but not massless pions. This gives us the opportunity to remember the period in which I first met Peter Freund and also to summarise the

Quasilinear systems of Jordan block type and the mKP hierarchy J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200428
Lingling Xue and E V FerapontovHydrodynamic type systems in Riemann invariants arise in a whole range of applications in fluid dynamics, Whitham averaging procedure, differential geometry and the theory of Frobenius manifolds. In this paper we discuss parabolic (Jordan block) analogues of diagonalisable systems. Our main observation is that integrable quasilinear systems of Jordan block type are parametrised by solutions of the

Iterative classical superadiabatic algorithm for combinatorial optimization J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200428
Takuya HatomuraWe consider a classical and superadiabatic version of an iterative quantum adiabatic algorithm to solve combinatorial optimization problems. This algorithm is deterministic because it is based on purely classical dynamics, that is, it does not rely on any stochastic approach to mimic quantum dynamics. Moreover, we use the exact shortcut to adiabaticity for stationary states of classical spin systems

Geometrical versus timeseries representation of data in quantum control learning J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200426
M Ostaszewski, J A Miszczak and P SadowskiRecently, machine learning techniques have become popular for analysing physical systems and solving problems occurring in quantum computing. In this paper we focus on using such techniques for finding the sequence of physical operations implementing the given quantum logical operation. In this context we analyse the flexibility of the data representation and compare the applicability of two machine

The critical behaviors and the scaling functions of a coalescence equation J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200423
Xinxing Chen, Victor Dagard, Bernard Derrida and Zhan ShiWe show that a coalescence equation exhibits a variety of critical behaviors, depending on the initial condition. This equation was introduced a few years ago to understand a toy model studied by Derrida and Retaux to mimic the depinning transition in presence of disorder. It was shown recently that this toy model exhibits the same critical behaviors as the equation studied in the present work. Here

Nonlocal gauge equivalence: Hirota versus extended continuous Heisenberg and Landau–Lifschitz equation J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200423
Julia Cen, Francisco Correa and Andreas FringWe exploit the gauge equivalence between the Hirota equation and the extended continuous Heisenberg equation to investigate how nonlocality properties of one system are inherited by the other. We provide closed generic expressions for nonlocal multisoliton solutions for both systems. By demonstrating that a specific autogauge transformation for the extended continuous Heisenberg equation becomes

Influence of interactions on the anomalous quantum Hall effect J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200423
C X Zhang and M A ZubkovThe anomalous quantum Hall conductivity in the 2 + 1 D topological insulators in the absence of interactions may be expressed as the topological invariant composed of the twopoint Green function. For the noninteracting system this expression is the alternative way to represent the TKNN invariant. It is widely believed that in the presence of interactions the Hall conductivity is given by the same

Recoverability from direct quantum correlations J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200419
S Di Giorgio, P Mateus and B MeraWe address the problem of compressing density operators defined on a finite dimensional Hilbert space which assumes a tensor product decomposition. In particular, we look for an efficient procedure for learning the most likely density operator, according to ‘Jaynes’ principle, given a chosen set of partial information obtained from the unknown quantum system we wish to describe. For complexity reasons

Quantum origin of the Minkowski space J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200419
Grzegorz PlewaWe show that D = 4 Minkowski space is an emergent concept related to a class of operators in extended Hilbert space with no positivedefinite scalar product. We start with the idea of positionlike and momentumlike operators (Plewa 2019 J. Phys. A: Math. Theor. 52 375401), introduced discussing a connection between quantum entanglement and geometry predicted by ER = EPR conjecture. We examine eigenequations

Unbreakable ##IMG## [http://ej.iop.org/images/17518121/53/19/195701/toc_aab7f68ieqn1.gif] {$\mathcal{PT}$} symmetry and its consequence in a ##IMG## [http://ej.iop.org/images/17518121/53/19/195701/toc_aab7f68ieqn2.gif] {$\mathcal{PT}$} symmetric dimer J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200419
J Ramya Parkavi and V K ChandrasekarThis article presents a finite dimensional unbreakable ##IMG## [http://ej.iop.org/images/17518121/53/19/195701/aab7f68ieqn3.gif] {$\mathcal{PT}$} symmetric waveguide system with linear and nonlinear coupling. In traditional ##IMG## [http://ej.iop.org/images/17518121/53/19/195701/aab7f68ieqn4.gif] {$\mathcal{PT}$} symmetric systems, a balance (or a symmetric state) among the waveguides with loss

An evolution model with eventbased extinction J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200419
Luiz Renato Fontes, Carolina Grejo and Fábio Sternieri MarquesWe propose a variation of the Guiol–Machado–Schinazi (GMS) model of evolution of species. In our version, as in the GMS model, at each birth, the new species in the system is labeled with a random fitness, but in our variation, to each extinction event is associated a random threshold and all species with fitness below the threshold are removed from the system. We present necessary and suficient criteria

Stochastic resetting and applications J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200419
Martin R Evans, Satya N Majumdar and Grégory SchehrIn this topical review we consider stochastic processes under resetting, which have attracted a lot of attention in recent years. We begin with the simple example of a diffusive particle whose position is reset randomly in time with a constant rate r , which corresponds to Poissonian resetting, to some fixed point (e.g. its initial position). This simple system already exhibits the main features of

Odd supersymmetrization of elliptic R matrices J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200419
A Levin, M Olshanetsky and A ZotovWe study a general ansatz for an odd supersymmetric version of the Kronecker elliptic function, which satisfies the genus one Fay identity. The obtained result is used for construction of the odd supersymmetric analogue for the classical and quantum elliptic R matrices. They are shown to satisfy the classical Yang–Baxter equation and the associative Yang–Baxter equation. The quantum Yang–Baxter equation

Thermodynamics of quantum phase transitions of a Dirac oscillator in a homogenous magnetic field J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200419
A M Frassino, D Marinelli, O Panella and P RoyThe Dirac oscillator in a homogeneous magnetic field exhibits a chirality phase transition at a particular (critical) value of the magnetic field. Recently, this system has also been shown to be exactly solvable in the context of noncommutative quantum mechanics featuring the interesting phenomenon of reentrant phase transitions. In this work we provide a detailed study of the thermodynamics of such

Energy partition for anharmonic, undamped, classical oscillators J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200419
Michał Mandrysz and Bartłomiej DybiecUsing stochastic methods, general formulas for average kinetic and potential energies for anharmonic, undamped (frictionless), classical oscillators are derived. It is demonstrated that for potentials of  x  ν , ( ν > 0) type energies are equipartitioned for the harmonic potential only. For potential wells weaker than parabolic potential energy dominates, while for potentials stronger than parabolic

Particle theory at Chicago in the late sixties and p Adic strings J. Phys. A: Math. Theor. (IF 2.11) Pub Date : 20200419
Paul H FramptonAs a contribution requested by the editors of a memorial volume for Peter G O Freund (1936–2018) we recall the lively particle theory group at the Enrico Fermi Institute of the University of Chicago in the late sixties, of which Peter was a memorable member. We also discuss a period some twenty years later when our and Peter’s research overlapped on the topic of p Adic strings.