Measuring $\mu_{B}$ at the LHC with ALICE

TL;DR

This paper presents an improved and most precise measurement of the baryon chemical potential $$ in high-energy Pb-Pb collisions at the LHC, using antiparticle-to-particle ratios from ALICE data to enhance understanding of particle production.

Contribution

It introduces a new, more precise method for measuring  using antiparticle-to-particle ratios in heavy-ion collisions at the LHC.

Findings

 measured as 0.7 b3 3.8 MeV in previous work.

New measurement reduces uncertainty significantly.

Provides the most precise  value to date.

Abstract

The baryon chemical potential $\mu_B$ is a fundamental parameter for the statistical mechanical description of particle production in heavy-ion collisions: its value encodes the average net baryon content of the fireball at chemical freeze-out. The first $\mu_B$ measurement in high-energy Pb-Pb collisions at the LHC was published in 2018 in Nature, and it was found that $\mu_B=0.7\pm3.8$ MeV. In this contribution, an improved $\mu_B$ measurement based on the study of antiparticle-to-particle ratios for protons, $^3\mathrm{He}$ and hypertriton ($^3_\Lambda\mathrm{H}$) using the data collected by ALICE in Run 2 of the LHC, is presented. The isospin chemical potential is also determined via the $\pi^-/\pi^+$ ratio. The obtained $\mu_B$ represents the most precise measurement available.