Studio della produzione di J/ψ in collisioni protone-protone a √s = 7 TeV con l’apparato ALICE

The work presented in this thesis is about the study of J/ψ production in proton-proton collision at √s = 7 TeV with the ALICE experiment at the LHC. The measurement, based on the statistics collected during 2010 with the M.B. trigger (Lint = 5.6nb-1), is performed at central rapidity in the dielectron channel (J/ψ → e+e-). The fraction of J/ψ from the decay of long-lived beauty hadrons was determined for J/ψ candidates with transverse momentum pt > 1.3GeV/c and rapidity |y| < 0.9. The results are compared to QCD model predictions. The shape of the pt and y distributions of b-quarks predicted by perturbative QCD model calculations are used to extrapolate the measured cross section to derive the bb pair total cross section and dσ/dy at mid-rapidity.