Integral equations for thermodynamics of the osp(1|2s) integrable spin chain

TL;DR

This paper introduces a finite set of nonlinear integral equations to compute the free energy of the osp(1|2s) integrable spin chain at finite temperatures, simplifying the thermodynamic analysis compared to traditional methods.

Contribution

The authors develop a novel set of NLIE for the osp(1|2s) spin chain that involves fewer unknown functions, using T-system and quantum transfer matrix techniques.

Findings

Derived NLIE for osp(1|2s) spin chain free energy

Calculated high temperature expansion of free energy and specific heat

Simplified thermodynamic analysis compared to traditional TBA equations

Abstract

We propose a system of nonlinear integral equations (NLIE), which gives the free energy of the osp(1|2s) integrable spin chain at finite temperatures. In contrast with usual thermodynamic Bethe ansatz equations, our new NLIE contain only a finite number of unknown functions. On deriving NLIE, we use our osp(1|2s) version of the T-system and the quantum transfer matrix method. Based on our NLIE, we also calculate the high temperature expansion of the free energy and the specific heat.