Magnetic effects in the Hadron Resonance Gas

TL;DR

This paper models the hadronic phase of QCD under magnetic fields using the hadron resonance gas approach, highlighting issues with higher-spin states and comparing charge fluctuations with lattice data.

Contribution

It identifies limitations of the HRG model in magnetic fields, especially regarding higher-spin states, and discusses charge fluctuations and neutral resonance behavior.

Findings

Rapid increase in proton yields with magnetic field due to higher-spin state issues

Qualitative discrepancies between HRG predictions and lattice QCD data for charge fluctuations

Neutral resonance behavior analyzed via detailed balance principles

Abstract

We discuss the modeling of the hadronic phase of QCD at finite magnetic field in the framework of hadron resonance gas (HRG). We focus on the statistical description of particle yields that include contribution from resonance decays. We demonstrate that the swift increase in the number of protons with magnetic field predicted in the HRG is due to the ill-defined description of higher-spin states. We discuss fluctuations of conserved charges and show that at present the qualitative comparison of the model predictions with the Lattice QCD data should be treated with care. We also discuss the principle of detailed balance which allows to study the magnetic field dependence of neutral resonances.