Prompt D*+ production in proton-proton and lead-lead collisions, measured with the ALICE experiment at the CERN Large Hadron Collider

In this thesis the results are presented of the first measurements of the D*+ meson nuclear modification factor RAA in heavy ion collisions at the Large Hadron Collider (LHC) using the ALICE (A Large Ion Collider Experiment) detector at CERN. These open charmed mesons are a useful tool to investigate the properties of the Quark-Gluon Plasma (QGP) since their parent charm quarks are produced in the early stages of heavy ion collisions, so that they are sensitive to the full formation history of the QGP, and their high mass limits their energy loss in the medium. Baseline measurements of charm production in proton-proton collisions have also been performed, since they are required to form the understanding of charm production and suppression in the QGP. The pT-differential inclusive production yield of prompt D*+ mesons, in the rapidity range |y|<0.5 and the pT range 2-36 GeV/c, in sqrt{sNN} = 2.76 TeV lead-lead collisions is shown. The nuclear modification factor (RAA), with respect to the proton-proton reference obtained and scaled down to a centre-of-mass energy of 2.76 TeV, is the determined. This has been done for both the data accumulated over 2010 and 2011, but for different collision centrality ranges. For the dataset with the largest amount of data (2011) this was the 0-7.5\% centrality class. For this the D*+ production yield is suppressed up to a factor five in the 8-12 GeV/c transverse momentum bin. This is in agreement with measurements of other charmed mesons measured in the ALICE experiment. Several models qualitatively describe the observed suppression, but the uncertainties from the measurements do not allow to identify one particular model as a preferred description, though the lattice QCD model can be excluded