/ Experiment-HEP CERN-PH-EP-2012-227

D_s meson production at central rapidity in proton--proton collisions at sqrt(s) = 7 TeV

Abstract: The pt-differential inclusive production cross section of the prompt charm-strange meson D_s in the rapidity range |y|&lt;0.5 was measured in proton--proton collisions at sqrt(s)=7 TeV at the LHC using the ALICE detector. The analysis was performed on a data sample of 2.98 10^8 events collected with a minimum-bias trigger. The corresponding integrated luminosity is L_int=4.8 nb^-1. Reconstructing the decay D_s -.> phi pi, with phi -> KK, and its charge conjugate, about 480 D_s mesons were counted, after selection cuts, in the transverse momentum range 2&lt;pt&lt;12 GeV/c. The results are compared with the prediction of a model based on perturbative QCD. The ratios of the cross sections of four D meson species (namely D^0, D^+, D*^+ and D_s) were determined both as a function of pt and integrated over pt after extrapolating to full pt range, together with the strangeness suppression factor in charm fragmentation. The obtained values are found to be compatible within uncertainties with those measured by other experiments in e+e-, ep and pp interactions at various centre-of-mass energies.

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