Producción de núcleos de deuterio y antideuterio en el experimento ALICE del LHC

This thesis reports the measurements of the invariant differential cross section of deuterons and antideuterons in proton-proton collisions at the center of mass energies of 900 GeV, 2.76 TeV and 7 TeV from 0.8 GeV/c to 3 GeV/c in transverse momentum and rapidity |y| < 0.5. It also reports the first ever measurements in proton-proton collisions of the invariant differential cross sections of antitritons from 1.2 GeV/c to 1.8 GeV/c, and antihelium-3 nuclei from 1.2 GeV/c to 6 GeV/c in transverse momentum. It has been observed that the independence with energy of the coalescence parameter, B2, is valid at LHC energies, and that the values of this parameter for deuterons and antideuterons are compatible. Moreover, the antideuteron/deuteron ratio is consistent with the square of the antiproton/proton ratio and the measurements show an increase of the B2 parameter with transverse momentum. It has also been found that the coalescence parameter of antitritons and antihelium-3 nuclei, B3, is consistent with the square of the B2 parameter and with the measurements of proton-nucleus collisions. On the other hand, the B2 parameter decreases in proton-proton events with high charged particle multiplicity, and the obtained values are consistent with the values extracted independently from the homogeneity lengths measured in two-pion Bose-Einstein correlations. Additionally, the deuteron/proton and antideuteron/antiproton ratios increase with charged particle multiplicity whereas antiproton/proton and antideuteron/deuteron ratios remain constant. Lastly, data indicate that heavier nuclei (A > 2) are produced preferentially in proton-proton events with high charged particle multiplicity.