arXiv subjects

Andrei G. Bytsko

Publications and source records attributed to Andrei G. Bytsko.

8 recordsLinked to original sources

arXiv2010

Non-Hermitian spin chains with inhomogeneous coupling

An open U_q(sl_2)-invariant spin chain of spin S and length N with inhomogeneous coupling is investigated as an example of a non-Hermitian (quasi-Hermitian) model. For several particular cases of such a chain, the ranges of the deformation parameter gamma are determined for which the spectrum of the model is real. For a certain range of gamma, a universal metric operator is constructed and thus the quasi-Hermiticity of the model is established. The constructed metric operator is non-dynamical, its structure is determined only by the symmetry of the model. The results apply, in particular, to all known homogeneous U_q(sl_2)-invariant integrable spin chains with nearest-neighbour interaction. In addition, the most general form of a metric operator for a quasi-Hermitian operator in finite dimensional space is discussed.

math-ph↗

arXiv2002

Haldane-Wu statistics and Rogers dilogarithm

The Haldane-Wu exclusion statistics is considered from the generalized extensive statistics point of view and certain related mathematical aspects are investigated. A series representation for the corresponding generating function is proven. Equivalence of two formulae for the central charge, derived for the Haldane-Wu statistics via the thermodynamic Bethe ansatz, is established. As a corollary, a series representation with a free parameter for the Rogers dilogarithm is found. It is shown that the generating function, the entropy, and the central charge for the Gentile statistics majorize those for the Haldane-Wu statistics (under appropriate choice of parameters). From this, some dilogarithm inequality is derived.

math-ph↗

arXiv2002

On integrable Hamiltonians for higher spin XXZ chain

Integrable Hamiltonians for higher spin periodic XXZ chains are constructed in terms of the spin generators; explicit examples for spins up to 3/2 are given. Relations between Hamiltonians for some U_q(sl_2)-symmetric and U(1)-symmetric universal r-matrices are studied; their properties are investigated. A certain modification of the higher spin periodic chain Hamiltonian is shown to be an integrable U_q(sl_2)-symmetric Hamiltonian for an open chain.

hep-th↗

arXiv2001

Thermodynamic Bethe ansatz for generalized extensive statistics

We investigate properties of the entropy density related to a generalized extensive statistics and derive the thermodynamic Bethe ansatz equation for a system of relativistic particles obeying such a statistics. We investigate the conformal limit of such a system. We also derive a generalized Y-system. The Gentile intermediate statistics and the statistics of gamma-ons are considered in detail. In particular, we observe that certain thermodynamic quantities for the Gentile statistics majorize those for the Haldane-Wu statistics. Specifically, for the effective central charges related to affine Toda models we obtain nontrivial inequalities in terms of dilogarithms.

hep-th↗

arXiv2000

Singularities of the Seiberg-Witten map

We construct an explicit solution of the Seiberg-Witten map for a linear gauge field on the non-commutative plane. We observe that this solution as well as the solution for a constant curvature diverge when the non-commutativity parameter theta reaches certain event horizon in the theta-space. This implies that an ordinary Yang-Mills theory can be continuously deformed by the Seiberg-Witten map into a non-commutative theory only within one connected component of the theta-space.

hep-th↗

arXiv1999

Two-term dilogarithm identities related to conformal field theory

We study 2x2 matrices A such that the corresponding TBA equations yield c[A] in the form of the effective central charge of a minimal Virasoro model. Certain properties of such matrices and the corresponding solutions of the TBA equations are established. Several continuous families and a discrete set of admissible matrices A are found. The corresponding two-term dilogarithm identities (some of which appear to be new) are obtained. Most of them are proven or shown to be equivalent to previously known identities.

math-ph↗

arXiv1997

Fusion of q-tensor operators: quasi-Hopf-algebraic point of view

Tensor operators associated with a given quantum Lie algebra admit a natural description in the R-matrix language. Here we employ the R-matrix approach to discuss the problem of fusion of tensor operators. The most interesting case is provided by the quantum WZNW model, where, by construction, we deal with sets of linearly independent tensor operators. In this case the fusion problem is equivalent to construction of an analogue F(p) of the twisting element F which is employed in Drinfeld's description of quasi-Hopf algebras. We discuss the construction of the twisting element F(p) in a general situation and give illustrating calculations for the case of the fundamental representation of U_q(sl(2)).

q-alg↗

arXiv1995

Tensor operators in R-matrix approach

The definitions and some properties (e.g. the Wigner-Eckart theorem, the fusion procedure) of covariant and contravariant q-tensor operators for quasitriangular quantum Lie algebras are formulated in the R-matrix language. The case of U_q(sl(n)) (in particular, for n=2) is discussed in more detail.

q-alg↗