Hadroproduction of heavy mesons in perturbative QCD

The hadroproduction of mesons containing a b quark is analyzed in perturbative QCD. This analysis is performed to the fourth order in the coupling constant alpha(s) for the production of two quark pairs and employs the model of weak binding of quarks in the meson. The minimum transverse momentum above which the differential spectrum of mesons can be reliably described in the factorization model assuming that hard b-quark production is followed by fragmentation into mesons is determined. At low transverse momenta of the product meson, there are significant contributions from nonfragmentation mechanisms that are described by the full set of QCD diagrams of a given order in alpha(s). The nonfragmentation diagrams interfere destructively with the fragmentation diagrams for z = 2E/root (s) over cap values that are close to unity.