Nonlinear dynamics of spin and charge in spin-Calogero model

TL;DR

This paper investigates the nonlinear spin and charge dynamics in the integrable spin-Calogero model, deriving hydrodynamic equations and analyzing non-equilibrium behaviors, revealing a connection to the Haldane-Shastry model at strong coupling.

Contribution

It derives classical hydrodynamic equations for the spin-Calogero model and explores non-equilibrium spin-charge dynamics, linking to known models at large coupling.

Findings

Hydrodynamic equations reduce to decoupled Riemann-Hopf equations.

Analysis of non-equilibrium configurations before gradient catastrophe.

Connection to Haldane-Shastry model in strong coupling limit.

Abstract

The fully nonlinear dynamics of spin and charge in spin-Calogero model is studied. The latter is an integrable one-dimensional model of quantum spin-1/2 particles interacting through inverse-square interaction and exchange. Classical hydrodynamic equations of motion are written for this model in the regime where gradient corrections to the exact hydrodynamic formulation of the theory may be neglected. In this approximation variables separate in terms of dressed Fermi momenta of the model. Hydrodynamic equations reduce to a set of decoupled Riemann-Hopf (or inviscid Burgers') equations for the dressed Fermi momenta. We study the dynamics of some non-equilibrium spin-charge configurations for times smaller than the time-scale of the gradient catastrophe. We find an interesting interplay between spin and charge degrees of freedom. In the limit of large coupling constant the hydrodynamics reduces to the spin hydrodynamics of the Haldane-Shastry model.