Magnetic Field Effects on Hadron Yields and Fluctuations

TL;DR

This study investigates how external magnetic fields influence hadron yields and fluctuations in a thermalized system, revealing that magnetic fields significantly affect certain yield ratios but do not alter fluctuation dynamics, thus limiting their informational value.

Contribution

It introduces an expanded Thermal-FIST package to analyze magnetic field effects on hadron yields and fluctuations within the HRG model, highlighting the proton-to-pion ratio as a potential magnetometer.

Findings

Magnetic field enhances the proton-to-pion ratio via $ riangle(1232)^{++}$ decay feeddown.

Magnetic field does not induce additional dynamical fluctuations.

Fluctuations offer limited extra information about magnetic fields beyond mean yields.

Abstract

We explore the impact of an external magnetic field on hadron yields and fluctuations in a thermalized system within the hadron resonance gas (HRG) model using an expanded Thermal-FIST package. The magnetic field sizably enhances the final proton-to-pion (p/$\pi$) ratio due to $\Delta(1232)^{++}$ decay feeddown indicating that this ratio may serve as a potential magnetometer for freeze-out conditions. At the same time, magnetic field does not generate additional dynamical fluctuations of hadron numbers. This suggests that fluctuations in heavy-ion collisions provide limited additional information about the magnetic field beyond what is already inferred from mean multiplicities.