卷 201, 编号 2 (2019)

We propose a relativistic generalization of integrable systems describing M interacting elliptic gl(N) Euler-Arnold tops. The obtained models are elliptic integrable systems that reproduce the spin elliptic GL(M) Ruijsenaars-Schneider model with N = 1 and relativistic integrable GL(N) elliptic tops with M = 1. We construct the Lax pairs with a spectral parameter on the elliptic curve.

In the large-N limit, we study saddle points of two SYK chains coupled by an interaction that is nonlocal in Euclidean time. We study the free model with the order of the fermionic interaction q = 2 analytically and also investigate the model with interaction in the case q = 4 numerically. We show that in both cases, there is a nontrivial phase structure with an infinite number of phases. Each phase corresponds to a saddle point in the noninteracting two-replica SYK. The nontrivial saddle points have a nonzero value of the replica-nondiagonal correlator in the sense of quasiaveraging if the coupling between replicas is turned off. The nonlocal interaction between replicas thus provides a protocol for turning the nonperturbatively subleading effects in SYK into nonequilibrium configurations that dominate at large N. For comparison, we also study two SYK chains with local interaction for q = 2 and q = 4. We show that the q=2 model has a similar phase structure, while the phase structure differs in the q = 4 model, dual to the traversable wormhole.

We consider the one-dimensional Boltzmann equation \(f_t+cf_x+(\mathcal{F}f)_c=0\) with a function \(\mathcal{F}\) depending on (t,x,c,f) and obtain the complete group classification of such equations in the class of point changes of whole set of variables (t,x,c,f). for this, we impose additional conditions on the transformations for the invariance of (a) the relations dx = c dt and \(dc=\mathcal{F}dt\), (b) the lines dt = dx = 0, and (c) the form f dx dc, which fix the physical meaning of the used variables and the relations between them.

for the Ising model with nonmagnetic dilution, we consider a method for constructing the “pseudochaotic” impurity distribution based on the condition that the position correlation of movable impurity atoms in neighboring sites vanishes. For the one-dimensional Ising model with nonmagnetic dilution, we find the exact solution and show that the pseudochaotic approximation method gives the exact value of the magnetic susceptibility for this model in a zero external field. We assume that the pseudochaotic impurity distribution is completely uncorrelated in the region of zero magnetization for any lattice. This assumption is based on calculating the correlation functions for the Ising model with nonmagnetic dilution on the Bethe lattice. We find the magnetic susceptibility for that model.

On page 252 in the first column of Table 3.2, D_n should be D_2n.