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

Abstract

Results on the production of ${}^4\text{He}$ and ${}^4\overline{\text{He}}$ 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 $\mathrm{d}N/\mathrm{d}{y}_{{}^4\overline{\mathrm{He}}}=(1.1\pm 0.4(\mathrm{stat})\pm 0.2(\mathrm{syst}))\times 10^{-6}$, 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 $1.4\pm 0.8(\mathrm{stat})\pm 0.5(\mathrm{syst})$.

17 pages, 3 captioned figures, 1 table, authors from page 12, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/4087