Abstract
| In ultrarelativistic heavy-ion collisions, the QCD matter is under extreme conditions of energy density, forming a quark-gluon plasma (QGP), in which quarks and gluons are deconfined. At RHIC and LHC energies, a large baryon-to-meson ratio, like Λ/K0SΛ/K0S, was observed within the transverse momentum range 2<pT<62<pT<6 GeV/cc for central heavy-ion collisions. The goal of this dissertation is to verify if the baryon-to-meson enhancement is only due to collective effects of the bulk of matter, and if there is also a contribution related to in-medium modifications of parton fragmentation. With two-hadron angular correlations, the K0SK0S and ΛΛ produced in association to an energetic hadron (hard processes) are separated from those originated from the thermalised medium (soft processes). The differential Λ/K0SΛ/K0S ratios related to the soft or hard production processes are extracted. The results are obtained for the Pb--Pb collisions at √sNN√sNN= 2.76 TeV recorded in 2011 with the ALICE experiment. Keywords: heavy-ion collisions, quark-gluon plasma, ALICE, baryon-to-meson ratio, hard processes, parton fragmentation, thermalised medium, bulk. |