<x>_{u-d} from lattice QCD at nearly physical quark masses

TL;DR

This study computes the second Mellin moment of the isovector quark distribution function from lattice QCD near physical quark masses, showing the lattice results approach experimental values as quark mass decreases.

Contribution

It provides a non-perturbative lattice QCD calculation of <x>_{u-d} at nearly physical quark masses, bridging the gap between theory and experiment.

Findings

Lattice results approach experimental values as quark mass decreases.

Non-perturbative renormalization was used to convert schemes.

Results are obtained at a pseudoscalar mass of 157 MeV.

Abstract

We determine the second Mellin moment of the isovector quark parton distribution function <x>_{u-d} from lattice QCD with N_f=2 sea quark flavours, employing the non-perturbatively improved Wilson-Sheikholeslami-Wohlert action at a pseudoscalar mass of 157(6) MeV. The result is converted non-perturbatively to the RI'-MOM scheme and then perturbatively to the MSbar scheme at a scale mu = 2 GeV. As the quark mass is reduced we find the lattice prediction to approach the value extracted from experiments.