$\mathrm{K}^{0}_\mathrm{S}$ and $\Lambda$ production associated to high-$p_\mathrm{T}$ particles in Pb-Pb collisions at $\sqrt{s_\mathrm{NN}}$ = 2.76 TeV with ALICE: Comparison between soft- and hard-processes in hadron production

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 $\Lambda/\mathrm{K}^{0}_\mathrm{S}$, was observed within the transverse momentum range $2 < p_\mathrm{T} < 6$ GeV/$c$ 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 $\mathrm{K}^{0}_\mathrm{S}$ and $\Lambda$ produced in association to an energetic hadron (hard processes) are separated from those originated from the thermalised medium (soft processes). The differential $\Lambda/\mathrm{K}^{0}_\mathrm{S}$ ratios related to the soft or hard production processes are extracted. The results are obtained for the Pb--Pb collisions at $\sqrt{s_\mathrm{NN}}$= 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.