Helicity-dependent distribution of strange quarks in the proton from nonlocal chiral effective theory

TL;DR

This paper calculates the helicity-dependent strange quark distribution in the proton using a nonlocal chiral effective theory, finding a small, negative lowest moment consistent with recent QCD analyses.

Contribution

It introduces a nonlocal chiral SU(3) effective field theory approach to compute the polarized strange quark distribution in the proton.

Findings

The polarized strange quark distribution is small and negative.

The lowest moment of Δs is negative.

Results align with recent global QCD analyses.

Abstract

The helicity-dependent strange quark distribution in the proton, $\Delta s$, is calculated in a nonlocal chiral SU(3) effective field theory. The hadronic proton to meson plus octet or decuplet baryon splitting functions are derived at the one-loop level, with loop integrals rendered finite by correlation functions introduced in the nonlocal Lagrangian. Within the convolution framework, the proton strange helicity distribution is obtained using spin-flavor symmetry to constrain the input valence quark distributions in the hadronic intermediate states. The polarized strange quark distribution is found to be quite small, with the lowest moment of $\Delta s$ negative, but consistent with recent global QCD analyses.