CTEQ6 parton distributions with heavy quark mass effects

Previously published CTEQ6 parton distributions adopt the conventional zero-mass parton scheme since the corresponding hard cross sections are universally available. For precision observables which are sensitive to charm and bottom quark mass effects, we provide in this paper an improved CTEQ6HQ parton distribution set determined in the more general variable flavor number scheme that incorporates heavy flavor mass effects. We describe in detail the QCD scheme and analysis procedure used, examine the predominant features of the new distributions, and compare them with previous distributions.