Inclusive D*(+/-) production in two photon collisions at LEP

In this thesis I present my results on the measurement of the open charm production in two-photon collision events done with the L3 detector at Large Electron Positron machine (LEP). The data sample was collected from 1997 through 2000 at center-of-mass energies ranging from 183 GeV to 209 GeV, corresponding to a total integrated luminosity of 683.4pb −1. The open charm production in two-photon collision events extrapolated to the full phase space is estimated to be: s&parl0;e+e-&rarrr;e +e-cc&d1;X&parr0;=9 23±69±109±222pb. The differential cross sections d s /dpT(D*±) and d s /d:η(D*±): are also measured as functions of transverse momentum pT(D*±) and the absolute value of pseudorapidity :η(D*±):, respectively. A fit to the data estimating the relative contributions of Direct and Resolved open charm production mechanisms is performed, giving (28.7 ± 5.6)% and (71.3 ± 8.8)%, respectively. Using those relative fractions, the Direct and Resolved process cross sections yield: s&parl0;e+e-&rarrr;e +e-cc&d1;X&parr0; direct=197±39±26±47 pb, s&parl0;e+e-&rarrr;e +e-cc&d1;X&parr0; resolved=749±93±106±180 pb. There are, however, large theoretical uncertainties in the separate measurement of the Direct and Resolved cross sections. The total open charm cross section in the full phase space and differential cross sections have been compared to the theoretical predictions and do not reveal disagreement with the next-to-leading order perturbative QCD calculations. ^