PDF fit in the fixed-flavor-number scheme

Abstract

We discuss the heavy-quark contribution to deep inelastic scattering in the scheme with $n_f=3,4,5$ fixed flavors. Based on the recent ABM11 PDF analysis of world data for deep-inelastic scattering and fixed-target data for the Drell-Yan process with the running-mass definition for heavy quarks we show that fixed flavor number scheme is sufficient for describing the deep-inelastic-scattering data in the entire kinematic range. We compare with other PDF sets and comment on the implications for measuring the strong coupling constant ${\alpha }_s(M_Z)$.

Comments: 11 pages with 10 figures, to appear in the proceedings of the "Ringberg Workshop: New Trends in HERA Physics 2011", Ringberg Castle, Germany, 25-28 September, 2011