Low temperature TBA and GHD for simple integrable QFT

TL;DR

This paper derives low-temperature thermodynamic and hydrodynamic equations for integrable quantum field theories, with numerical solutions for the sinh-Gordon model, enhancing understanding of virtual processes and quasiparticle spectra.

Contribution

It introduces corrected thermodynamic Bethe ansatz and generalized hydrodynamics equations for integrable QFTs at low temperatures, including numerical solutions and velocity spectrum analysis.

Findings

Numerical solutions of TBA for sinh-Gordon model

Explicit GHD equations for small virtual quasiparticle occupation

Spectrum of velocities computed for linear GHD approximation

Abstract

We derive the low temperature thermodynamic equations corrected by virtual processes for integrable QFT on large but finite size space circle. Obtained TBA's are solved numerically for the sinh-Gordon model. We also derive corresponding Euler scale generalized hydrodynamic (GHD) equations and display them explicitly for small occupation ratio of virtual quasiparticles. The spectrum of velocities for the linear approximation to GHD is numerically calculated.