On the role of heavy flavor parton distributions at high energy colliders

We compare 'fixed flavor number scheme' (FFNS) and 'variable flavor number scheme' (VFNS) parton model predictions at high energy colliders. Based on our recent LO- and NLO-FFNS dynamical parton distributions, we generate radiatively two sets of VFNS parton distributions where also the heavy quark flavors h=c,b,t are considered as massless partons within the nucleon. By studying the role of these distributions in the production of heavy particles (hh¯, tb¯, hW±, Higgs-bosons, etc.) at high energy ep, pp¯ and pp colliders, we show that the VFNS predictions are compatible with the FFNS ones (to within about 10-20% at LHC, depending on the process) when the invariant mass of the produced system far exceeds the mass of the participating heavy quark flavor.