Towards quantitative precision for QCD at large densities

TL;DR

This paper advances the functional renormalisation group method to better understand the phase structure of QCD at high densities, incorporating comprehensive multi-scattering effects for more reliable quantitative predictions.

Contribution

It introduces a self-consistent approximation scheme in a low energy quark-meson model to improve quantitative analysis of QCD at large densities.

Findings

Computed the phase diagram of QCD at high densities and low temperatures.

Demonstrated the importance of multi-scattering effects in phase structure predictions.

Discussed the systematic extension and reliability of the approach.

Abstract

QCD at large density reveals a rich phase structure, ranging from a potential critical end point and inhomogeneous phases or moat regimes to color superconducting ones with competing order effects. Resolving this region in the phase diagram of QCD with functional approaches requires a great deal of quantitative reliability, already for a qualitative access. In the present work, we systematically extend the functional renormalisation group approach to low energy QCD by setting up a fully self-consistent approximation scheme in a low energy effective quark-meson theory. In this approximation, all pointlike multi-scattering events of the mesonic pion and the sigma mode are taken into account in terms of an effective potential as well as all higher quark-antiquark-mesonic scattering orders. As a first application we compute the phase structure of QCD including its low temperature - large chemical potential part. The quantitative reliability of the approximation and systematic extensions are also discussed.