Renormalization group improved pressure for cold and dense QCD

TL;DR

This paper applies the renormalization group optimized perturbation theory to evaluate the pressure of cold, dense QCD with three massless quark flavors, achieving improved agreement with higher-order perturbative results and reduced scale sensitivity.

Contribution

The study introduces RGOPT as a non-perturbative, renormalization group invariant method for calculating QCD pressure at two-loop level, outperforming standard pQCD in accuracy and stability.

Findings

RGOPT results align better with higher-order perturbative calculations.

RGOPT shows less dependence on the renormalization scale.

Provides a potential alternative to lattice simulations at high densities.

Abstract

We apply the renormalization group optimized perturbation theory (RGOPT)to evaluate the QCD (matter) pressure at the two-loop level considering three flavors of massless quarks in a dense and cold medium. Already at leading order ($\alpha_s^0$), which builds on the simple one loop (RG resummed) term, our technique provides a non-trivial non-perturbative approximation which is completely renormalization group invariant. At the next-to-leading order the comparison between the RGOPT and the pQCD predictions shows that the former method provides results which are in better agreement with the state-of-the-art $higher \, order$ perturbative results, which include a contribution of order $\alpha_s^3 \ln^2 \alpha_s$. At the same time one also observes that the RGOPT predictions are less sensitive to variations of the arbitrary $\bar{\rm MS}$ renormalization scale than those obtained with pQCD. These results indicate that the RGOPT provides an efficient resummation scheme which may be considered as an alternative to lattice simulations at high baryonic densities.