Nature of finite temperature and density phase transitions in many-flavor QCD

TL;DR

This study explores the phase transitions in many-flavor QCD at finite temperature and density, focusing on the conditions for first order transitions relevant to baryogenesis and how heavy flavor mass and chemical potential influence these transitions.

Contribution

It provides a detailed analysis of the critical heavy flavor mass and the impact of chemical potential on the phase structure in many-flavor QCD, informing real-world QCD behavior.

Findings

Critical heavy flavor mass increases with Nf.

First order region widens with higher chemical potential.

Finite density effects extend the first order transition region.

Abstract

We investigate the phase structure of (2+Nf)-flavor QCD, where two light flavors and Nf massive flavors exist, to discuss the feasibility of the electroweak baryogenesis in realistic technicolor scenario and to understand properties of finite density QCD. Because an appearance of a first order phase transition at finite temperature is a necessary condition for the baryogenesis, it is important to study the nature of finite temperature phase transition. Applying the reweighting method, the probability distribution function of the plaquette is calculated in the many-flavor QCD. Through the shape of the distribution function, we determine the critical mass of heavy flavors terminating the first order region, and find it to become larger with Nf. We moreover study the critical line at finite density and the first order region is found to become wider as increasing the chemical potential. We discuss how the properties of real (2+1)-flavor QCD at finite temperature and density can be extracted from simulations of many-flavor QCD.