xFitter 2.0.0: Heavy quark matching scales: Unifying the FFNS and VFNS

xFitter is an open-source package that provides a framework for thedetermination of the parton distribution functions (PDFs) of theproton for many different kinds of analyses in Quantum Chromodynamics(QCD). It incorporates experimental data from a wide range ofexperiments including fixed-target, Tevatron, HERA, and LHC. xFitterversion 2.0.0 has recently been released, and offers an expanded setof tools and options. The new xFitter 2.0.0 program links to theAPFEL code which has implemented generalized matching conditions thatenable the switch from NF to NF+1 active flavors at an arbitrarymatching scale mu_m. This enables us to generalize the transitionbetween a FFNS and a VFNS and essentially vary continuously between thetwo schemes; in this sense the matching scale mu_m allows us to unifythe FFNS and VFNS in a common framework. This paper provides a briefoverview of xFitter with emphasis of these new features.