Non-strange quark stars within resummed QCD

TL;DR

This paper applies a novel resummation technique, RGOPT, to evaluate the equation of state for non-strange cold quark matter, resulting in more accurate mass-radius relations for quark stars that align with observed pulsars.

Contribution

It introduces the use of RGOPT for modeling non-strange quark stars, demonstrating improved scale dependence and compatibility with astrophysical observations compared to traditional pQCD.

Findings

RGOPT provides efficient resummation of perturbative series.

Mass-radius relations match observed pulsar data.

Scale dependence is significantly reduced with RGOPT.

Abstract

The recently developed resummation technique known as {\it renormalization group optimized perturbation theory} (RGOPT) is employed in the evaluation of the EoS describing non-strange cold quark matter at NLO. Inspired by recent investigations, which suggest that stable quark matter can be made only of up and down quarks, the mass-radius relation for two flavor pure quark stars is evaluated and compared with the predictions from perturbative QCD (pQCD) at NNLO. This comparison explicitly shows that by being imbued with renormalization group properties, and a variational optimization procedure, the method allows for an efficient resummation of the perturbative series. Remarkably, when the renormalization scale is chosen so as to reproduce maximum mass stars with M=$2-2.3M_\odot$, one obtains a mass-radius curve compatible with the masses and radii of the pulsars PSR J0740+6620, PSR J0030+0451, and the compact object HESS J1731-347. Moreover, the scale dependence of the EoS (and mass-radius relation) obtained with the RGOPT is greatly improved when compared to that of pQCD. This seminal application to the description of quark stars shows that the RGOPT represents a robust alternative to pQCD when describing compressed quark matter.