Measurement of charm production at central rapidity in proton-proton collisions at root s=7 TeV

The p t-differential production cross sections of the prompt (B feed-down subtracted) charmed mesons D0, D+, and D*+ in the rapidity range |y| < 0.5, and for transverse momentum 1 < p t  < 12 GeV/c, were measured in proton-proton collisions at s√=2.76TeV with the ALICE detector at the Large Hadron Collider. The analysis exploited the hadronic decays D0 → K−π+, D+ → K−π+π+, D*+ → D0π+, and their charge conjugates, and was performed on a Lint=1.1nb−1 event sample collected in 2011 with a minimum-bias trigger. The total charm production cross section at s√=2.76TeV and at 7 TeV was evaluated by extrapolating to the full phase space the p t-differential production cross sections at s√=2.76TeV and our previous measurements at s√=7TeV . The results were compared to existing measurements and to perturbative-QCD calculations. The fraction of cd− D mesons produced in a vector state was also determined.