On the extraction of the intrinsic light-quark sea in the proton

TL;DR

This paper analyzes recent HERMES data on strange-quark distributions in the proton, highlighting how assumptions affect results and discussing implications for the intrinsic light-quark sea, with findings consistent with a significant intrinsic strange-quark component.

Contribution

It clarifies the impact of analysis assumptions on strange-quark distribution results and discusses the potential existence of an intrinsic strange-quark sea in the proton.

Findings

HERMES data do not exclude a significant intrinsic strange-quark sea.

The $x$ dependence of the $(s+ar s)/(ar u+ ar d)$ ratio supports intrinsic strange content.

Assumptions in the analysis significantly influence the interpretation of $S(x)$ results.

Abstract

The HERMES collaboration recently reported a reevaluation of the strange-quark parton distribution, $S(x)$, based on kaon production in semi-inclusive deep-inelastic scattering. Two distinct results on $S(x)$ at the $x> 0.1$ region, one with a sizable magnitude and another with a vanishing content, were reported. We show that the latter result is due to a particular assumption adopted in the analysis. The impact of the new HERMES $S(x)$ result on the extraction of intrinsic light-quark sea in the proton is discussed. Given the large uncertainty in the kaon fragmentation function, we find that the latest HERMES data do not exclude the existence of a significant intrinsic strange-quark sea in the proton. The $x$ dependence of the $(s+\bar s)/(\bar u+ \bar d)$ ratio is also in qualitative agreement with the presence of intrinsic strange-quark sea.