Production of light nuclei and anti-nuclei in pp and Pb-Pb collisions at LHC energies

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2.76 TeV
7 TeV
Abstract Plain Text: 

The production of (anti-)deuteron, (anti-)triton and (anti-)3He nuclei in pp collisions at $\sqrt{s} = 7$ TeV
and in Pb-Pb collisions at $\sqrt{s_{\rm NN}} = 2.76$ TeV has been measured using the ALICE detector at
the LHC. The Pb-Pb spectra exhibit a significant hardening with increasing centrality due to radial
flow demonstrating that they show signatures of the evolution to the kinetic freeze-out. This behavior is
demonstrated by combined blast-wave fits of several particles. The integrated particle yields are discussed
with respect to coalescence and thermal-statistical model expectations. The particle ratios, d/p and 3He/p,
in Pb-Pb collisions are found to be in agreement with a common chemical freeze-out temperature of
$T_{\rm chem} \approx 156$ MeV while the d/p ratio in pp collisions is lower by a factor of 2.5 than in Pb-Pb collisions.
Furthermore, no significant centrality dependence in these ratios is observed, favoring coalescence models in which nuclei
production is proportional to particle density instead of absolute particle multiplicity. Using source parameters from two-pion HBT
analyzes in the coalescence approach, one can successfully approximate the deuteron and 3He data illustrating that
both processes are governed by the same lengths of homogeneity.

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