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

TL;DR

xFitter 2.0.0 introduces a unified framework for heavy quark matching scales, enabling continuous transition between FFNS and VFNS schemes in proton PDF analyses within QCD.

Contribution

The paper presents the integration of generalized matching conditions in xFitter 2.0.0, allowing flexible switching between FFNS and VFNS schemes at arbitrary scales.

Findings

Unified treatment of FFNS and VFNS schemes.

Implementation of continuous transition between schemes.

Enhanced analysis capabilities for proton PDFs.

Abstract

xFitter is an open-source package that provides a framework for the determination of the parton distribution functions (PDFs) of the proton for many different kinds of analyses in Quantum Chromodynamics (QCD). It incorporates experimental data from a wide range of experiments including fixed-target, Tevatron, HERA, and LHC. xFitter version 2.0.0 has recently been released, and offers an expanded set of tools and options. The new xFitter 2.0.0 program links to the APFEL code which has implemented generalized matching conditions that enable the switch from $N_F$ to $N_F+1$ active flavors at an arbitrary matching scale $\mu_m$. This enables us to generalize the transition between a FFNS and a VFNS and essentially vary continuously between the two schemes; in this sense the matching scale $\mu_m$ allows us to unify the FFNS and VFNS in a common framework. This paper provides a brief overview of xFitter with emphasis of these new features.