High-order baryon number fluctuations within the fRG approach

TL;DR

This paper uses the functional renormalization group approach to compute high-order baryon number fluctuations at finite temperature and density, successfully matching lattice and experimental results and explaining non-monotonic behaviors in collision energy dependence.

Contribution

It introduces a QCD-assisted low energy effective field theory combined with the FRG approach to accurately calculate baryon fluctuations, capturing non-monotonic trends observed experimentally.

Findings

Fourth- and sixth-order fluctuations match lattice results at zero density.

Results are consistent with experimental measurements.

Non-monotonic kurtosis dependence on collision energy explained by chiral crossover.

Abstract

We compute high-order baryon number fluctuations at finite temperature and density within a QCD-assisted low energy effective field theory. Quantum, thermal and density fluctuations are incorporated with the functional renormalization group approach. Quantum and in-medium fluctuations are encoded via the evolution of renormalization group flow equations. The resulting fourth- and sixth-order baryon number fluctuations meet the lattice benchmark results at vanishing density. They are consistent with experimental measurements, and in particular, the non-monotonic dependence of the kurtosis of net-baryon number distributions on the collision energy is observed in our calculations. This non-monotonicity arises from the increasingly sharpened chiral crossover with the decrease of collision energy.