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

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.