Speaker
Description
The ALICE collaboration has measured the production of light-flavour hadrons in pp, p--Pb and Pb--Pb collisions at$\sqrt{s\rm{_{NN}}} = $ 5.02 TeV over a wide range of transverse momentum ($p_{\rm T}$). The results on $\pi$, K, p,K$^{*0}$ and $\phi$ $p_{\rm T}$ spectra, ratios of the $p_{\rm T}$-integrated yields and mean transverse momentum will be presented for the three colliding systems at the same energy ($\sqrt{s_{\rm{NN}}}$ = 5.02 TeV), and compared as a function of average charged particle multiplicity measured at mid-rapidity. It will be shown that the production of these particles follows a continuous trend as a function of multiplicity across the three systems. Identified particle ratios provide information on the composition and the thermal properties of the medium. The measurement of short-lived hadronic resonance production and their ratio to stable hadron species, such as $\phi/$K and K$^{*0}/$K, is used to infer information on the hadronic phase.
Parton energy loss is investigated by determining the nuclear modification factor ($R\mathrm{_{AA}}$). The production of light-flavour hadrons in the most central Pb--Pb collisions relative to pp collisions is found to be strongly suppressed at high $p\rm{_T}$ ($>$ 8 GeV/$c$), whereas in p--Pb collisions the nuclear modification factors are consistent with unity. This indicates that the strong suppression of high-$p\rm{_T}$ hadrons measured in central Pb--Pb collisions is not due to an initial state effect but instead to the energy loss of partons traversing a hot and dense QCD medium. A similar suppression is observed for all the measured light-flavour hadrons at $p\rm{_T}$ $>$ 8 GeV/$c$. This suggests that the partonic energy loss in the medium for light quark flavors ($u, d, s$) is independent of flavour.