Production of heavy quarks and heavy quarkonia

Abstract

Uncertainties in the next-to-leading-order calculations of heavy-quark (Q) production are investigated. Preductions for total cross sections, single-inclusive distributions of heavy quarks and heavy flavoured hadrons, as well as for$Q\bar Q$ correlations, are compared with charm and bottom data. The description of heavy-quarkonium production requires a separation of the short-distance scale of$Q\bar Q$ production, which is set by the heavy-quark mass from the longer-distance scales associated with the bound-state formation. Various factorization approaches are compared, in particular with respect to the different constraints imposed on the colour and angular-momentum states of the$Q\bar Q$ pair(s) within a specific quarkonium state. Theoretical predictions are confronted with data on heavy-quarkonium production at fixed-target experiments and also at$p\bar p$ colliders, where fragmentation gives the leading-twist cross section in 1/p ² _T and 1/m ² at high transverse momentum.