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

Results on the production of ${}^4\text{He}$ and ${}^4\overline{\text{He}}$ nuclei in Pb-Pb collisions at $\sqrt{s_{\mathrm{N}\mathrm{N}}}=2.76$ 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 $$\mathrm{d}$N/$\mathrm{d}$y _{^{4}$\mathrm{H}\mathrm{e}$} = (0.8 \pm 0.4 ~($\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{t}$) \pm 0.3~($\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t}$))\times 10^{-6}$and$$\mathrm{d}$N/$\mathrm{d}$y _{^{4}$\overline{\mathrm{H}\mathrm{e}}$} = (1.1 \pm 0.4~($\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{t}$) \pm 0.2~($\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t}$))\times 10^{-6}$, respectively. This is in agreement with the statistical thermal model expectation assuming the same chemical freeze-out temperature ($T_{\mathrm{c}\mathrm{h}\mathrm{e}\mathrm{m}}$ = 156 MeV) as for light hadrons. The measured ratio of ${}^4\overline{\mathrm{H}\mathrm{e}}$/${}^4\mathrm{H}\mathrm{e}$ is $1.4 \pm 0.8~($\mathrm{s}\mathrm{t}\mathrm{a}\mathrm{t}$) \pm 0.5~($\mathrm{s}\mathrm{y}\mathrm{s}\mathrm{t}$)$.