The Lattice NJL Model at Non-zero Baryon and Isospin Densities

TL;DR

This paper investigates the chiral symmetry restoring transition in the (3+1)-D NJL model at finite baryon and isospin densities, using novel numerical methods to handle the sign problem.

Contribution

The study introduces two approaches—partially quenched and imaginary isospin chemical potential simulations—to explore the phase transition in the NJL model with non-zero isospin chemical potential.

Findings

Initial results on the phase transition behavior.

Methods to circumvent the sign problem in simulations.

Insights into the effects of isospin density on chiral symmetry.

Abstract

We present initial results of a numerical investigation of the chiral symmetry restoring transition in the (3+1)-dimensional Nambu -- Jona-Lasinio model with both non-zero baryon chemical potential (mu_B) and isospin chemical potential (mu_I). With non-zero isospin chemical potential, the model suffers from a sign problem. We proceed in two ways: (i) We perform ``partially quenched'' simulations in which mu_I is made non-zero only during the measurement of chiral observables; (ii) We perform full simulations with imaginary isospin chemical potential with the aim to analytically continue results to real mu_I.