Heavy quark effects on parton distribution functions in the unpolarized virtual photon up to the next-to-leading order in QCD

TL;DR

This paper explores how heavy quark masses influence the parton distribution functions in unpolarized virtual photons, using next-to-leading order QCD calculations with a focus on mass effects and scheme dependence.

Contribution

It introduces a formalism incorporating heavy quark mass effects into the evolution of parton distributions in virtual photons at NLO in QCD, including initial conditions and operator matrix elements.

Findings

Heavy quark mass effects significantly alter the parton distributions.

The results depend on the factorization scheme used.

The formalism provides a consistent way to include heavy quark effects in photon PDFs.

Abstract

We investigate the heavy quark mass effects on the parton distribution functions in the unpolarized virtual photon up to the next-to-leading order in QCD. Our formalism is based on the QCD-improved parton model described by the DGLAP evolution equation as well as on the operator product expansion supplemented by the mass-independent renormalization group method. We evaluate the various components of the parton distributions inside the virtual photon with the massive quark effects, which are included through the initial condition for the heavy quark distributions, or equivalently from the matrix element of the heavy quark operators. We discuss some features of our results for the heavy quark effects and their factorization-scheme dependence.