Vector-type four-quark interaction and its impact on QCD phase structure

TL;DR

This paper investigates how a vector-type four-quark interaction influences the QCD phase diagram using the PNJL model, focusing on the imaginary chemical potential region to inform real-world QCD behavior.

Contribution

It analytically clarifies the effects of vector-type four-quark interactions on QCD phase structure and proposes a method to determine interaction strength via lattice simulations.

Findings

Chiral condensate and quark number density are sensitive to the interaction strength.

The study clarifies the Roberge-Weiss periodicity and symmetry properties with the interaction.

A method is proposed to estimate the interaction strength from lattice data.

Abstract

Effects of the vector-type four-quark interaction on QCD phase structure are investigated in the imaginary chemical potential region, by using the Polyakov-loop extended Nambu-Jona-Lasinio (PNJL) model with the extended Z3 symmetry. In the course to this end, we clarify analytically the Roberge-Weiss periodicity and symmetry properties of various quantities under the existence of a vector-type four-quark interaction. In the imaginary chemical potential region, the chiral condensate and the quark number density are sensitive to the strength of the interaction. Based on this result, we propose a possibility to determine the strength of the vector-type interaction, which largely affects QCD phase structure in the real chemical potential region, by comparing the results of lattice simulations and effective model calculations in the imaginary chemical potential region.