Measurements of D-hadron azimuthal correlations with ALICE at the LHC

This thesis describes the analysis of azimuthal correlations between $\rm{D}^{0}$ mesons and unidentified charged particles, in pp collisions at $\sqrt{s} = 7$ TeV, performed on the data collected with the ALICE experiment at the LHC. Perspectives for the analysis in p-Pb and Pb-Pb collisions are also discussed. Two-particle azimuthal correlations, where at least one is a charmed hadron, are an important tool to study in better details the charm production. In pp collisions, these measurements allow us to investigate the fragmentation and hadronization of charm quarks, as well as to descrive the properties of charm jets. In addition, this analysis can give us access to the different charm production mechanisms. The various pQCD hard processes for $c\overline{c}$ production, indeed, result in different $\Delta\phi$ distributions between the two heavy quarks. This feature can be exploited to disentangle the contribution to charm production from the different processes, by analyzing the azimuthal correlations of the quark hadronization products, as the D mesons. In particular, the study of D-hadron correlations allows us to gain information on the quark pair by analyzing the features of the correlation peaks at $\Delta\phi = 0$ and $\Delta\phi = \pi$. In Pb-Pb, charm azimuthal correlation studies allow us to measure the parton energy loss in the fireball from a different point of view, with respect to the usual measurements of modification of the transverse momentum spectra of charged hadrons. Modifications of the $\Delta\phi$ correlation pattern between charmed hadrons and charged particles, especially on the away side, are sensitive to the energy loss of charm quarks in the QGP medium and allow us, in addition, to quantify how this energy loss affects the jet production. Performing the same study in p-Pb collisions can help to disentangle the cold nuclear matter effects, present in both p-Pb and Pb-Pb collision systems, from the modifications due to the presence of the QGP, produced only in Pb-Pb collisions.