We investigate the stability of a uniform elliptical vortex in a two-dimensional incompressible Euler fluid. It is demonstrated that for small eccentricities, the vortex relaxes to a core-halo structure that undergoes rigid rotation with the central core remaining nearly elliptical. For large eccentricities, the vortex splits into two quasi-circular vortices that revolve around the center of mass.

We consider new generalized statistics based on the generalization of statistical weight. We work out the thermodynamic curvature of an ideal gas with particles obeying such generalized statistics. For different values of generalization parameters; p and q , we observe that both attractive and repulsive intrinsic statistical interaction is expected. As long as p ⩾ q , the thermodynamic curvature is

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More than a century has passed since van’t Hoff and Arrhenius formulated their celebrated rate theories, but there are still elusive aspects in the temperature-dependent phase transition kinetics of molecular systems. Here I present a theory based on microcanonical thermostatistics that establishes a simple and direct temperature dependence for all rate constants, including the forward and the reverse

We consider the two-dimensional classical XY model on a square lattice in the thermodynamic limit using tensor renormalization group and precisely determine the critical temperature corresponding to the Berezinskii–Kosterlitz–Thouless (BKT) phase transition to be 0.89290(5) which is an improvement compared to earlier studies using tensor network methods.

The statistical description of a one-dimensional superdiffusive Lévy flier restricted to a finite domain is well known to be technically involving. For example, in this type of process the probability distribution P ( x , t ) and survival probability S ( t ) cannot be obtained from the method of images. Other methods, such as the fractional derivative approach, also find technical difficulties due

Ensemble averages of a stochastic model show that, after a formation stage, the tips of active blood vessels in an angiogenic network form a moving two dimensional stable diffusive soliton, which advances toward sources of growth factor. Here we use methods of multiple scales to find the diffusive soliton as a solution of a deterministic equation for the mean density of active endothelial cells tips

In this work we consider general fermion systems in two spatial dimensions, both with and without charge conservation symmetry, which realize a non-trivial fermionic topological order with only Abelian anyons. We address the question of precisely how these quantum phases differ from their bosonic counterparts, both in terms of their edge physics and in the way one would identify them in numerics. As

We give a Pfaffian formula to compute the partition function of the Ising model on any graph G embedded in a closed, possibly non-orientable surface. This formula can be considered as an extension of the generalised Kac–Ward formula in Cimasoni (2010 J. Stat. Mech. P07023) to the case of non-orientable surfaces. By combining the ideas of Loebl–Masbaum (2011 Adv. Math. 226 332–49), Tesler (2000 J. Comb

Entanglement or modular Hamiltonians play a crucial role in the investigation of correlations in quantum field theories. In particular, in 1 + 1 space–time dimensions, the spectra of entanglement Hamiltonians of conformal field theories (CFTs) for certain geometries are related to the spectra of the physical Hamiltonians of corresponding boundary CFTs. As a result, conformal invariance allows exact

The totally asymmetric exclusion process (TASEP) is an outstanding paradigm of self-driven particle models. A new two-channel TASEP model with short-range interactions in horizontal and vertical directions is given. The dynamic properties of the system with periodic boundary and open boundary are investigated by computer simulation and theoretical analysis. The analysis results based on the cluster

Using the idea of the quantum inverse scattering method, we introduce the operators B ( x ), C ( x ) and ##IMG## [http://ej.iop.org/images/1742-5468/2020/8/083101/jstataba0aaieqn1.gif] {$\tilde {\mathbf{B}}\left(x\right),\tilde {\mathbf{C}}\left(x\right)$} corresponding to the off-diagonal entries of the monodromy matrix T for the phase model and i -boson model in terms of bc fermions and neutral fermions

Many real transportation and mobility networks have their vertices placed on the surface of the Earth. In such embeddings, the edges laid on that surface may cross. In his pioneering research, Moon analyzed the distribution of the number of crossings on complete graphs and complete bipartite graphs whose vertices are located uniformly at random on the surface of a sphere assuming that vertex placements

We use the Fokker–Planck equation as a starting point for studying the orientational probability distribution of an active Brownian particle (ABP) in ( d + 1) dimensions (i.e. d angular dimensions and 1 radial dimension). This Fokker–Planck equation admits an exact solution in series form which is, however, unwieldy to use because of poor convergence for short and intermediate times. We present an

The inverse problem of ‘eigenstates-to-Hamiltonian’ is considered for an open chain of N quantum spins in the context of many-body-localization. We first construct the simplest basis of the Hilbert space made of 2 N orthonormal matrix-product-states (MPS), that will thus automatically satisfy the entanglement area-law. We then analyze the corresponding N local integrals of motions (LIOMs) that can

We report on the calculation of the symmetry resolved entanglement entropies in two-dimensional many-body systems of free bosons and fermions by dimensional reduction . When the subsystem is translational invariant in a transverse direction, this strategy allows us to reduce the initial two-dimensional problem into decoupled one-dimensional ones in a mixed space-momentum representation. While the idea

The Dyson equation for the real two-time commutator retarded one-magnon Green function of the ferromagnetically polarized XX chain is suggested following the Plakida–Tserkovnikov algorithm. Starting from this result a low-temperature integral representation for the corresponding magnon self-energy is obtained by the truncated form factor expansion, however, without any resummations. Within the suggested

We study the phase diagram, both at zero and finite temperature, in a class of ##IMG## [http://ej.iop.org/images/1742-5468/2020/7/073107/jstataba0a1ieqn1.gif] {${\mathbb{Z}}_{q}$} models with infinite-range interactions. We are able to identify the transitions between a symmetry-breaking and a trivial phase by using a mean-field approach and a perturbative expansion. We perform our analysis on a Hamiltonian

The notion of tree-shifts constitutes an intermediate class between one-sided shift spaces and multidimensional ones. This paper proposes an algorithm for computing the entropy of a tree-shift of finite type. Meanwhile, the entropy of a tree-shift of finite type is ##IMG## [http://ej.iop.org/images/1742-5468/2020/7/073412/jstataba0a0ieqn1.gif] {$\frac{1}{p} \mathrm{ln} \lambda $} for some ##IMG## [http://ej

We present a quantum Monte Carlo algorithm for the simulation of general quantum and classical many-body models within a single unifying framework. The algorithm builds on a power series expansion of the quantum partition function in its off-diagonal terms and is both parameter-free and Trotter error-free. In our approach, the quantum dimension consists of products of elements of a permutation group

The cavity master equation (CME) is a closure scheme to the usual master equation representing the dynamics of discrete variables in continuous time. In this work we explore the CME for a ferromagnetic model in a random graph. We first derive and average equation of the CME that describes the dynamics of mean magnetization of the system. We show that the numerical results compare remarkably well with

The stochastic dynamics of zipping/unzipping transition of a DNA hairpin is theoretically investigated within the framework of generalized Langevin equation in a complex cellular environment. Analytical expressions of the distributions of transition path and first passage times are derived. The results reveal that the transition path time of DNA is shorter compared to the Kramers’s first passage time

Luggage-laden pedestrians are important traffic elements especially in public places such as railway stations, airports etc. In this study, experiments were performed with luggage-laden pedestrians walking and running to understand the properties of their movement including the way they carry luggage, their speed and their spatial distribution. It is found that their gender, position and speed all

The geometrical features of the (non-convex) loss landscape of neural network models are crucial in ensuring successful optimization and, most importantly, the capability to generalize well. While minimizers’ flatness consistently correlates with good generalization, there has been little rigorous work in exploring the condition of existence of such minimizers, even in toy models. Here we consider

We introduce the use of neural networks as classifiers on classical disordered systems with no spatial ordering. In this study, we propose a framework of design objectives for learning tasks on disordered systems. Based on our framework, we implement a convolutional neural network trained to identify the spin-glass state in the three-dimensional Edwards–Anderson Ising spin-glass model from an input

In this paper, we investigated the unstable periodic orbits of a nonlinear chaotic generalized Lorenz-type system. By means of the variational method, appropriate symbolic dynamics are put forward, and the homotopy evolution approach, which can be used in the initialization of the cycle search, is introduced. Fourteen short unstable periodic orbits with different topological lengths, under specific

We consider a system of two coupled oscillators one of which is driven parametrically and investigate both classical and quantum dynamics within Floquet description. Characteristic changes in the time evolution of the quantum fluctuations are observed for dynamically stable and unstable regions. Dynamical instability generated by the parametrically driven oscillator leads to infinite temperature thermalization

Multiple relaxation channels often arise in the dynamics of liquids where the momentum current associated to the particle-conservation law splits into distinct contributions. Examples are strongly confined liquids for which the currents in lateral and longitudinal direction to the walls are very different, or fluids of nonspherical particles with distinct relaxation patterns for translational and rotational

One three-site non-rigid model with two polar covalent bonds is proposed for electrolyte solvent; this model is integrated into the inhomogeneous electrolyte fluid classical density functional theory (CDFT) framework by means of the modified interfacial statistical association fluid theory. With the CDFT, we investigate surface electrostatic force (SEF) between two similarly charged planar surface

Synchronization among arrays of beating cilia is one of the emergent phenomena in biological processes at mesoscopic scales. Strong inter-ciliary couplings modify the natural beating frequencies, ω , of individual cilia to produce a collective motion that moves around a group frequency ω m . Here we study the thermodynamic cost of synchronizing cilia arrays by mapping their dynamics onto a generic

We study the dynamics of symmetric exclusion process (SEP) in the presence of stochastic resetting to two possible specific configurations—with rate r 1 (respectively, r 2 ) the system is reset to a step-like configuration where all the particles are clustered in the left (respectively, right) half of the system. We show that this dichotomous resetting leads to a range of rich behaviour, both dynamical

On several one-dimensional (1D) and 2D nonbipartite lattices, we study both free and Hubbard interacting lattice fermions when some magnetic fluxes are threaded or gauge fields coupled. First, we focus on finding out the optimal flux which minimizes the energy of fermions at specific fillings. For spin-1/2 fermions at half-filling on a ring lattice consisting of odd-numbered sites, the optimal flux

We investigate parking in a one-dimensional lot, where cars enter at a rate λ and each attempts to park close to a target at the origin. Parked cars also depart at rate 1. An entering driver cannot see beyond the parked cars for more desirable open spots. We analyze a class of strategies in which a driver ignores open spots beyond τL , where τ is a risk threshold and L is the location of the most distant

In this work the anomalous diffusion in the quenched trap model with diverging mean waiting times is examined. The approach of randomly stopped time is extensively applied in order to obtain asymptotically exact representation of the disorder averaged positional probability density function. We establish that the dimensionality and the geometric properties of the lattice, on top of which the disorder

In the case of a fire, the presence of smoke sometimes makes people bend over and thus prevents them from walking upright. This feature of pedestrian movement in this situation is different from normal walking and affects the dynamics of an evacuation. However, the effect of such kind of motion on pedestrian traffic has not been systematically studied. Therefore, this paper studies the characteristics

Extending the concept of multi-selfsimilar random field, we study multi-scale invariant (MSI) fields with component-wise discrete scale invariant properties. Assuming scale parameters as λ i > 1, i = 1, …, d and the parameter space as (1, ∞) d , the first scale rectangle is referred to the rectangle (1, λ 1 ) ×⋯× (1, λ d ). We show that the covariance functions of the sampled Markov MSI field are characterized

Multiplicative cascades have been used in turbulence to generate fields with multifractal statistics and long-range correlations. Examples of continuous and causal stochastic processes which generate such a random field have been carefully discussed in the literature. Here a causal lognormal stochastic process is built to represent the dynamics of pseudo-dissipation in a Lagrangian trajectory. It is

Motivated by multiphase flow in reservoirs, we propose and study a two-species sandpile model in two dimensions. A pile of particles becomes unstable and topples if, at least one of the following two conditions is fulfilled: (1) the number of particles of one species in the pile exceeds a given threshold or (2) the total number of particles in the pile exceeds a second threshold. The latter mechanism

Statistical physics in equilibrium grants us one of its most powerful tools: the equipartition principle. It states that the degrees of freedom of a mechanical system act as a thermometer: temperature is equal to the mean variance of their oscillations divided by their stiffness. However, when a non-equilibrium state is considered, this principle is no longer valid. In our experiment, we study the

Recent analyses of least-sensitive inflection points in derivatives of the microcanonical entropy for the two-dimensional Ising model revealed higher-order transition signals in addition to the well-studied second-order ferromagnetic/paramagnetic phase transition. In this paper, we re-analyze the exact density of states for the one-dimensional Ising chain as well as the strips with widths/lengths of

We study a one-dimensional lattice of N sites each occupied by a mathematical 'polymer,' that is, is a binary random sequence of arbitrary length n , or equivalently, a rooted path of n links on an infinite binary tree. The average polymer length is controlled by the monomer fugacity z . A pair of polymers on adjacent sites carries a weight factor ω for each link on the tree that they have in common

The synchronization pattern of a fully connected competing Kuramoto model with a uniform intrinsic frequency distribution g ( ω ) was recently considered. This competing Kuramoto model assigns two coupling constants with opposite signs, K 1 < 0 and K 2 > 0, to the 1 − p and p fractions of nodes, respectively. This model has a rich phase diagram that includes incoherent, π, and travelling wave (TW)

Promoting cooperation in public goods games is a long-standing problem in multiple branches of science. Reward is an effective means of promoting cooperation, but can be costly if distributed on a large scale or over long periods of time. Avoiding excessive costs is naturally of critical concern. We introduce group rewarding into public goods games and explore the impacts of such rewarding on cooperation

We report a throughout analysis of the entanglement entropies related to different symmetry sectors in the low-lying primary excited states of a conformal field theory (CFT) with an internal U (1) symmetry. Our findings extend recent results for the ground state. We derive a general expression for the charged moments, i.e. the generalised cumulant generating function, which can be written in terms

We investigate the learning performance of the pseudolikelihood maximization method for inverse Ising problems. In the teacher–student scenario under the assumption that the teacher’s couplings are sparse and the student does not know the graphical structure, the learning curve and order parameters are assessed in the typical case using the replica and cavity methods from statistical mechanics. Our

Non-Fermi liquid and unconventional quantum critical points (QCP) with strong fractionalization are two exceptional phenomena beyond the classic condensed matter doctrines, both of which could occur in strongly interacting quantum many-body systems. This work demonstrates that using a controlled method one can construct a non-Fermi liquid within a considerable energy window based on the unique physics

In this paper, we focus on the problem of community detection by normalized-cut graph partitioning. The standard normalized-cut graph partitioning is to partition a graph into subgraphs by removing fewer edges and guaranteeing the number of vertices in subgraphs remains relatively balanced. However, the multiple nature of many networks cannot be captured only by binary edges. In order to detect the

Agricultural commodity futures are the earliest listed futures in the world. The rapid development of their markets has greatly affected the world agricultural production and circulation. Thereby, the volatility characteristics of agricultural futures markets and the cross-correlations between the futures and spot markets have attracted extensive attention from investors, regulators and researchers

Body rotation is a common behavior in pedestrian flow dynamics. In this paper, an improved least-effort model is proposed to reproduce this behavior and other pedestrian flow characteristics. In this model, the pedestrian chooses the velocity and angle of body rotation according to the minimum energy cost. The energy cost includes the caloric expenditure in the walking, collision loss and body rotation

Percolation transition in networks as edges are gradually added, can generate a variety of critical and supercritical behaviors. Here we report a percolation transition model with two parameters α and β , in which by decreasing the value of α from 1 to 0 the phase transition could change from continuous to multiple discontinuous and finally to discontinuous without supercritical region, and that the

In this paper, we propose a novel probability distribution that asymptotically represents a power-law, ψ ( t ) ∼ t − α −1 , with 0 < α < 2. The main feature of the distribution is that it has a simple expression in the Laplace transform representation, making it suitable for performing calculations in stochastic processes, particularly non-Poissonian processes.

We study the metastable equilibrium properties of the two-dimensional Potts model with heat-bath transition rates using a novel expansion. The method is especially powerful for large number of state spin variables and it is notably accurate in a rather wide range of temperatures around the phase transition.

In recent years, researchers have delved into the relationship between information and stochastic thermodynamics. In this paper, we apply the information geometry to discover the physical limitation in bacterial growth. By mapping the evolution of distribution to the motion on the hypersphere, we discover a relationship between evolutionary time and cost in the bacterial growth process. Through the

We study the bootstrap and diffusion percolation models in the simple-cubic (sc), body-centered cubic (bcc), and face-centered cubic (fcc) lattices using the Newman–Ziff algorithm. The percolation threshold and critical exponents were calculated through finite-size scaling with high precision in the three lattices. In addition to the continuous and first-order percolation transitions, we found a double

Entanglement witness is a Hermitian operator that is useful for detecting the genuine multipartite entanglement of mixed states. Nonlinear entanglement witnesses have the advantage of a wider detection range in the entangled region. We construct genuine entanglement witnesses for four qubits density matrices in the mutually unbiased basis. First, we find the convex feasible region with positive partial

The effect of particle overtaking on transport in a narrow channel is studied using a 1D model of a driven tracer in a quiescent bath. In contrast with the well-studied non-driven case, where the tracer’s long-time dynamics changes from sub-diffusive to diffusive whenever overtaking is allowed, the driven tracer is shown to exhibit a phase transition at a finite overtaking rate. The transition separates

The equilibrium properties of a Janus fluid confined to a one-dimensional channel are exactly derived. The fluid is made of particles with two faces (active and passive), so that the pair interaction is that of hard spheres, except if the two active faces are in front of each other, in which case the interaction has a square-well attractive tail. Our exact solution refers to quenched systems (i.e.

For the inverse square long-range ferromagnetic Ising chain in a transverse field, the thermal phase boundary of the floating Kosterlitz–Thouless phase is obtained for several values of the transverse field down to the quantum critical point. The sharp domain walls in the classical model are increasingly smeared out by the transverse field, which is evidenced by a pronounced broadening of the non-universal

We initiate a systematic study of high energy matrix elements of local operators in 2D CFT. Knowledge of these is required in order to determine whether the generalized eigenstate thermalization hypothesis (ETH) can hold in such theories. Most high energy states are high level Virasoro descendants, and by employing an oscillator representation of the Virasoro algebra we develop an efficient method

We examine the parliamentary presence data of the 2008–2012 and 2012–2016 legislatures of the Lithuanian parliament. We consider the cumulative presence series of each individual representative in the data set. These series exhibit superdiffusive behavior. We propose a modified noisy voter model as a model for the parliamentary presence. We provide detailed analysis of the anomalous diffusion of the