Production of $^{4}$He and $^{4}\overline{\textrm{He}}$ in Pb-Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ = 2.76 TeV at the LHC

TL;DR

This paper reports the first measurement of helium-4 and anti-helium-4 nuclei production in lead-lead collisions at the LHC, confirming thermal model predictions and providing insights into antimatter formation in high-energy nuclear collisions.

Contribution

First measurement of $^{4}$He and $^{4}ar{ extrm{He}}$ production in Pb-Pb collisions at 2.76 TeV, supporting thermal model predictions for antimatter production.

Findings

Measured yields are consistent with thermal model expectations.

The $^{4}ar{ extrm{He}}$/$^{4} extrm{He}$ ratio is approximately 1.4.

Results support statistical hadronization models for antimatter production.

Abstract

Results on the production of $^{4}{\textrm{He}}$ and $^{4}\overline{\textrm{He}}$ nuclei in Pb-Pb collisions at $ \sqrt{s_{\mathrm{NN}}} = 2.76 $ TeV in the rapidity range $ \mid y \mid < 1$, using the ALICE detector, are presented in this paper. The rapidity densities corresponding to 0-10% central events are found to be $\mathrm{d}N/\mathrm{d}y _{^{4}\mathrm{He}} = (0.8 \pm 0.4 ~(\mathrm{stat}) \pm 0.3~(\mathrm{syst}))\times 10^{-6}$ and $\mathrm{d}N/\mathrm{d}y _{^{4}\mathrm{\overline{He}}} = (1.1 \pm 0.4~(\mathrm{stat}) \pm 0.2~(\mathrm{syst}))\times 10^{-6}$, respectively. This is in agreement with the statistical thermal model expectation assuming the same chemical freeze-out temperature ($T_{\mathrm{chem}}$ = 156 MeV) as for light hadrons. The measured ratio of $^{4}\overline{\mathrm{He}}$/$^{4}\mathrm{He}$ is $1.4 \pm 0.8~(\mathrm{stat}) \pm 0.5~(\mathrm{syst})$.