Thermodynamic Study for Conformal Phase in Large Nf Gauge Theory

TL;DR

This study uses lattice QCD simulations to analyze the chiral phase transition in SU(3) gauge theory with varying fermion flavors, revealing how the transition behavior changes near the conformal window and discussing implications for preconformal dynamics.

Contribution

It provides new lattice simulation data on critical couplings and the Tc/Lambda_L ratio for different Nf, highlighting the approach to conformal behavior in large Nf regimes.

Findings

Critical couplings align with two-loop asymptotic scaling for Nt >= 6.

Tc/Lambda_L ratio increases significantly at Nf=8, indicating proximity to the conformal window.

Results support enhanced fermionic screening at higher Nf, affecting phase transition characteristics.

Abstract

We investigate the chiral phase transition at finite temperature (T) in colour SU(3) Quantum Chromodynamics (QCD) with six species of fermions (Nf = 6) in the fundamental representation. The simulations have been performed by using lattice QCD with improved staggered fermions. The critical couplings (bc) for the chiral phase transition are observed for several temporal extensions Nt, and the two-loop asymptotic scaling of the dimensionless ratio Tc/Lambda_L (Lambda_L = Lattice Lambda-parameter) is found to be achieved for Nt >= 6. Further, we collect bc at Nf = 0 (quenched), and Nf = 4 at a fixed Nt = 6 as well as Nf = 8 at Nt = 6 and 12, the latter relying on our earlier study. The results are consistent with enhanced fermionic screening at larger Nf. The ratio Tc/Lambda_L depends very mildly on Nf in the Nf = 0-4 region, begins increasing at Nf = 6, and significantly grows up at Nf = 8, as Nf reaches to the edge of the conformal window. We discuss the interrelation of the results with preconformal dynamics in the light of a functional renormalization group analysis.