Analysis of regulator and cutoff artifacts in the phase diagram of the quark-meson model

TL;DR

This paper investigates how different regulators and cutoff choices affect the results of the quark-meson model at finite temperature and chemical potential, highlighting the importance of renormalization-group consistency.

Contribution

It introduces a nontrivial parameter-fixing procedure to compare results across various regulators and cutoffs within the functional renormalization-group framework.

Findings

Regulator and cutoff dependences are minimal at low T and chemical potential.

Significant cutoff artifacts appear at high T and low chemical potential.

Regulator choice influences the dynamics near the first-order chiral phase transition.

Abstract

We study regulator and cutoff artifacts in the quark-meson model at finite temperature and quark chemical potential within the functional renormalization-group approach using the local potential approximation. To this end, we discuss the concept of renormalization-group consistency in effective models, which necessitates a nontrivial parameter-fixing procedure to enable a meaningful comparison of results obtained with different regulators and cutoffs. We employ a standard range of cutoff values used in phenomenological studies and regulators that differ significantly in their analytic properties as well as in their classification according to the principle of strongest singularity. We find that regulator and cutoff dependences are small at low temperatures and quark chemical potentials. At high temperatures and low quark chemical potentials, significant cutoff artifacts arise, whereas the properties of the regulator affect the dynamics in the regime governed by a chiral phase transition of first order at low temperatures and high quark chemical potentials.