Speaker
Domenico Elia
(INFN Bari)
Description
The ALICE experiment at CERN was designed to study the properties of the strongly-interacting hot and dense matter created in heavy-ion collisions at the LHC energies. Hard partons propagating through such a medium are predicted to lose energy via multiple scattering and gluon radiation. As a result, the yield of final-state hadrons at high transverse momentum will be suppressed compared to the reference value from a simple superposition of incoherent proton-proton collisions. This modification of the $p_T$ spectra, quantified by the nuclear modification factor ($R_{AA}$), allows to study the parton energy-loss mechanisms and medium properties.
The ALICE detector has specific and unique capabilities for measuring the production of strange and light-flavour hadrons over a wide range of transverse momentum, from pp and p-Pb interactions up to the highest-multiplicity environment of the central Pb-Pb collisions. Transverse momentum spectra at mid-rapidity for K$^0_S$, $\Lambda$, $\Xi^-$ and $\Omega^-$ (and corresponding antiparticles) have been measured both in pp and PbPb collisions at $\sqrt{s_{NN}}$ = 2.76 TeV. Results on the corresponding $R_{AA}$ as a function of the PbPb collision centrality will be presented and compared with those for identified charged hadrons ($\pi$, K and p). Features of the observed suppression patterns for hadrons with and without strangeness content and the corresponding calculations from theoretical models will be discussed in connection with the predicted energy loss dependence on the parton mass, while the comparison of baryon and meson suppressions at high $p_T$ will be proposed as potential probe of different energy losses for quarks and gluons.
Finally, $R_{AA}$ results will also be compared with the corresponding measurements carried out in p-Pb collisions at $\sqrt{s_{NN}}$ = 5.02 TeV ($R_{pPb}$), to investigate possible contributions due to cold nuclear matter (initial-state) effects.
Primary author
Domenico Elia
(INFN Bari)
