Unitarity and nonperturbative effects in the spin structure functions at small $x$

TL;DR

This paper investigates the small-$x$ behavior of spin structure functions $g_1(x)$ and $h_1(x)$ using a unitarized chiral quark model, revealing distinct low-$x$ dependencies and emphasizing unitarity effects.

Contribution

It introduces a combined approach of constituent quark structure, geometrical scattering, and unitarity to analyze spin structure functions at small $x$, predicting specific behaviors.

Findings

Non-diffractive singular behavior of $g_1(x)$ at small $x$

Diffractive smooth behavior of $h_1(x)$ at small $x

Unitarity effects significantly influence spin structure functions

Abstract

We consider low-$x$ behavior of the spin structure functions $g_1(x)$ and $h_1(x)$ in the unitarized chiral quark model that combines the ideas on constituent quark structure of hadrons with a geometrical scattering picture and unitarity. A nondiffractive singular low-$x$ dependence of $g^p_1(x)$ and $g_1^n(x)$ is obtained and a diffractive type smooth behavior of $h_1(x)$ is predicted at small $x$.