Probing Quark-Gluon Plasma by measurement of strange charm mesons production in pp and PbPb collisions with CMS detector

This thesis presents the first measurement of prompt D⁺_s mesons in heavy ion collisions with the CMS experiment. The transverse momentum (p_T) spectra of prompt D⁺_s mesons and charge conjugates are measured in pp and PbPb collisions at a center-of-mass energy of 5.02 TeV per nucleon pair using the CMS detector at the LHC. Themeasurement is performed through the D+s→φπ⁺→K⁺K⁻π⁺ decay channel with the D+s rapidity range |y| < 1.0. The D⁺_s production in the pT range from 2 (6)GeV/c to 40 GeV/c in pp (PbPb) collisions is measured. Suppression of the D+s nuclear modification factor (R_AA) in PbPb collisions suggests a significant interaction between charm quarks and the quark-gluon plasma. The double ratio of prompt D⁺_s to prompt D⁰ production in pp and PbPb is measured. The ratio is consistent witha PHSD model calculation and consistent with unity, which indicates that strange charm meson enhancement in PbPb collisions is not found in the measured p_T interval.