Measurement of charm production at central rapidity in proton-proton collisions at √s = 2.76\;TeV

A bstract The p t -differential production cross sections of the prompt (B feed-down subtracted) charmed mesons D 0 , 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 = 2.76\;TeV with the ALICE detector at the Large Hadron Collider. The analysis exploited the hadronic decays D 0 → K − π + , D + → K − π + π + , D* + → D 0 π + , and their charge conjugates, and was performed on a L_ int = 1.1\;nb^ - 1 event sample collected in 2011 with a minimum-bias trigger. The total charm production cross section at √s = 2.76\;TeV and at 7 TeV was evaluated by extrapolating to the full phase space the p t -differential production cross sections at √s = 2.76\;TeV and our previous measurements at √s = 7\;TeV . The results were compared to existing measurements and to perturbative-QCD calculations. The fraction of cd̄ D mesons produced in a vector state was also determined.