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

Submission Date: 
28/06/2015
Article Information
Submission Form
System: 
Pb-Pb
Energy: 
2.76 TeV
Abstract Plain Text: 

The production of the hypertriton nuclei $^{3}_{\Lambda}\mathrm H$  and $ ^{3}_{\overline{\Lambda}}\mathrm{\overline{H}} $ has been measured for the first time in Pb--Pb collisions at $\sqrt{s_{\mathrm{NN}}}$ =~2.76~TeV with the ALICE experiment at LHC. The $p_{\rm T}$-integrated  $^{3}_{\Lambda}\mathrm H$ yield in one unity of rapidity, 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 \mbox{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 $S_3$ = \hyp/(\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 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. 

Depends on https://aliceinfo.cern.ch/ArtSubmission/node/199