Do we expect light flavor sea-quark asymmetry also for the spin-dependent distribution functions of the nucleon?

TL;DR

This paper uses the chiral quark soliton model to predict and compare the flavor asymmetry in the spin-dependent sea-quark distributions of the nucleon with experimental data, highlighting a significant negative flavor asymmetry.

Contribution

It introduces a prediction of flavor asymmetry in polarized sea-quark distributions consistent with recent semi-phenomenological analyses.

Findings

The model explains qualitative features of unpolarized and polarized structure functions.

Predicts a sizable negative flavor asymmetry in polarized sea-quark distributions.

Shows qualitative agreement with recent experimental analyses.

Abstract

After taking account of the scale dependence by means of the standard DGLAP evolution equation, the theoretical predictions of the chiral quark soliton model for the unpolarized and longitudinally polarized structure functions of the nucleon are compared with the recent high energy data. The theory is shown to explain all the qualitative features of the experiments, including the NMC data for $F_2^p (x) - F_2^n (x)$, $F_2^n (x) / F_2^p (x)$, the Hermes and NuSea data for $\bar{d}(x) - \bar{u}(x)$, the EMC and SMC data for $g_1^p(x)$, $g_1^n(x)$ and $g_1^d(x)$. Among others, flavor asymmetry of the longitudinally polarized sea-quark distributions is a remarkable prediction of this model, i.e., it predicts that $\Delta \bar{d}(x) - \Delta \bar{u}(x) = C x^{\alpha} [ \bar{d}(x) - \bar{u}(x)]$ with a sizable negative coefficient $C \simeq -2.0$ (and $\alpha \simeq 0.12$) in qualitative consistency with the recent semi-phenomenological analysis by Morii and Yamanishi.