Soft pions at high energy and the flavor asymmetry of the light sea quarks in the nucleon

TL;DR

This paper explores how soft pion contributions at high energy influence the flavor asymmetry of light sea quarks in the nucleon, providing explanations for the NMC deficit and implications for sum rules.

Contribution

It demonstrates that soft pion theorems can account for the NMC deficit and estimates their impact on sum rules, highlighting the significance of high energy and small x regions.

Findings

Soft pion contributions explain the NMC deficit magnitude.

Soft pions have negligible impact on the Ellis-Jaffe sum rule.

Contribution to g_1^{ep} becomes positive below x=0.002.

Abstract

The modified Gottfried sum rule makes clear importance of the high energy region not only in the theoretical meaning but also in the numerical analysis. In this talk, it is shown that the soft pion theorem in the inclusive reaction at high energy can explain the magnitude about $0.02 \sim 0.04$ in the NMC deficit. The main contribution comes from the small $x$ region. We also estimate the soft pion contribution to the Ellis-Jaffe sum rule and show it to be negligible. However we find that the contribution to $g_1^{ep}$ becomes positive below $x = 0.002$.