\(^{3}_{\Lambda}\mathrm H\) and \(^{3}_{\bar{\Lambda}} \overline{\mathrm H}\) production in Pb-Pb collisions at \(\sqrt{s_{\rm NN}}\) = 2.76 TeV

Abstract

The production of the hypertriton nuclei \(^{3}_{\Lambda}\mathrm H\) and \(^{3}_{\bar{\Lambda}} \overline{\mathrm H}\) has been measured for the first time in Pb-Pb collisions at \(\sqrt{s_{\rm NN}}\) = 2.76 TeV with the ALICE experiment at LHC energies. The total yield, d\(N\)/d\(y\) \(\times \mathrm{B.R.}_{\left( ^{3}_{\Lambda}\mathrm H \rightarrow ^{3}\mathrm{He},\pi^{-} \right)} = \left( 3.86 \pm 0.77 (\mathrm{stat.}) \pm 0.68 (\mathrm{syst.})\right) \times 10^{-5}\) in the 0-10% most central collisions, is consistent with the predictions from a statistical thermal model using the same temperature as for the light hadrons. The coalescence parameter \(B_3\) shows a dependence on the transverse momentum, similar to the \(B_2\) of deuterons and the \(B_3\) of \(^{3}\mathrm{He}\) nuclei. The ratio of yields \(S_3\) = \(^{3}_{\Lambda}\mathrm H\). \(^{3}\mathrm{He}\) \(\times \Lambda/\mathrm{p}\) was measured to be \(S_3\) = 0.60 \(\pm\) 0.13 (stat.) \(\pm\) 0.21 (syst.) in 0-10% centrality events; this value is compared to different theoretical models. The measured \(S_3\) is fully compatible with thermal model predictions. The measured \(^{3}_{\Lambda}\mathrm H\) lifetime, \( \tau = 181^{+54}_{-39} (\mathrm{stat.}) \pm 33 (\mathrm{syst.})\ \mathrm{ps}\) is compatible within 1\(\sigma\) with the world average value.