$^{3}_Λ\mathrm H$ and $^{3}_{\barΛ} \overline{\mathrm H}$ production in Pb-Pb collisions at $\sqrt{s_{\rm NN}}$ = 2.76 TeV

Abstract

The production of the hypertriton nuclei $^{3}_Λ\mathrm H$ and $^{3}_{\barΛ} \overline{\mathrm H}$ 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$y$ $\times \mathrm{B.R.}_{\left( ^{3}_Λ\mathrm H \rightarrow ^{3}\mathrm{He},π^{-} \right)} = \left( 3.86 \pm 0.77 (\mathrm{stat.}) \pm 0.68 (\mathrm{syst.})\right) \times 10^{-5}$ 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 $S_3$ = $^{3}_Λ\mathrm H$/($^{3}\mathrm{He}$ $\times Λ/\mathrm{p}$) 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 $^{3}_Λ\mathrm H$ lifetime, $ τ= 181^{+54}_{-39} (\mathrm{stat.}) \pm 33 (\mathrm{syst.})\ \mathrm{ps}$ is compatible within 1$σ$ with the world average value.

21 pages, 7 captioned figures, 4 tables, authors from page 16, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/1700