Strange quark helicity in the proton from chiral effective theory

TL;DR

This paper calculates the polarized strange quark distribution in the proton using chiral effective theory, deriving comprehensive splitting functions and convolution formulas, and finds the distribution to be small and negative.

Contribution

It introduces a complete set of hadronic splitting functions within chiral SU(3) theory and derives model-independent relations for quark distribution moments.

Findings

Polarized strange quark distribution is small and mostly negative.

Derived convolution formulas linking hadronic and quark distributions.

Established model-independent relations for nonanalytic behavior of moments.

Abstract

We compute the helicity-dependent strange quark distribution in the proton in the framework of chiral effective theory. Starting from the most general chiral SU(3) Lagrangian that respects Lorentz and gauge invariance, we derive the complete set of hadronic splitting functions at the one meson loop level, including the octet and decuplet rainbow, tadpole, Kroll-Ruderman and octet-decuplet transition configurations. By matching hadronic and quark level operators, we obtain generalized convolution formulas for the quark distributions in the proton in terms of hadronic splitting functions and quark distributions in the hadronic configurations, and from these derive model-independent relations for the leading nonanalytic behavior of their moments. Within the limits of parameters of the Pauli-Villars regulators derived from inclusive hyperon production, we find that the polarized strange quark distribution is rather small and mostly negative.