Flavor decomposition of the nucleon unpolarized, helicity and transversity parton distribution functions from lattice QCD simulations

TL;DR

This paper uses lattice QCD simulations with the quasi-distribution approach to compute the flavor-decomposed unpolarized, helicity, and transversity parton distribution functions of the nucleon, including disconnected contributions.

Contribution

It presents the first lattice QCD determination of flavor-decomposed nucleon PDFs, including strange and disconnected contributions, using an ensemble with near-physical quark masses.

Findings

Non-zero disconnected isoscalar and strange quark distributions found.

Methodology includes hierarchical probing for disconnected loops.

Results provide valuable insights into poorly known strange quark PDFs.

Abstract

We present results on the quark unpolarized, helicity and transversity parton distributions functions of the nucleon. We use the quasi-parton distribution approach within the lattice QCD framework and perform the computation using an ensemble of twisted mass fermions with the strange and charm quark masses tuned to approximately their physical values and light quark masses giving pion mass of 260 MeV. We use hierarchical probing to evaluate the disconnected quark loops. We discuss identification of ground state dominance, the Fourier transform procedure and convergence with the momentum boost. We find non-zero results for the disconnected isoscalar and strange quark distributions. The determination of the quark parton distribution and in particular the strange quark contributions that are poorly known provide valuable input to the structure of the nucleon.