Phase structure of two-color QCD at real and imaginary chemical potentials; lattice simulations and model analyses

TL;DR

This study explores the phase diagram of two-color QCD at real and imaginary chemical potentials using lattice simulations and the PNJL model, assessing analytic continuation and model validity across different regions.

Contribution

It provides a comprehensive analysis of two-color QCD phase structure, testing analytic continuation and enhancing the PNJL model with baryon degrees and vector interactions.

Findings

Lattice results at imaginary mu can be analytically continued to real mu.

PNJL model accurately describes deconfinement but needs improvements in transition regions.

Including baryon degrees and vector interactions improves model-data agreement.

Abstract

We investigate the phase structure of two-color QCD at both real and imaginary chemical potentials mu, performing lattice simulations and analyzing the data with the Polyakov-loop extended Nambu--Jona-Lasinio (PNJL) model. Lattice QCD simulations are done on an 8^3 times 4 lattice with the clover-improved two-flavor Wilson fermion action and the renormalization-group improved Iwasaki gauge action. We test the analytic continuation of physical quantities from imaginary mu to real mu by comparing lattice QCD results calculated at real mu with the result of analytic function the coefficients of which are determined from lattice QCD results at imaginary mu. We also test the validity of the PNJL model by comparing model results with lattice QCD ones. The PNJL model is good in the deconfinement region, but less accurate in the transition and confinement regions. This problem is improved by introducing the baryon degree of freedom to the model. It is also found that the vector-type four-quark interaction is necessary to explain lattice data on the quark number density.