Study of the $ s-\bar s $ asymmetry in the proton

TL;DR

This paper investigates the $s-ar s$ asymmetry in the proton using the meson-baryon model, analyzing its dependence on model parameters and the evolution of distributions at different perturbative orders.

Contribution

It applies a simplified meson-baryon model to calculate the $s-ar s$ asymmetry and examines the impact of the cutoff parameter and evolution schemes on the results.

Findings

The $s-ar s$ asymmetry depends on the cutoff parameter $ ext{Lambda}$.

Evolution at NNLO with variable flavor number scheme is not suitable for intrinsic distributions.

Theoretical uncertainties are estimated based on parameter dependence.

Abstract

The study of $ s-\bar s $ asymmetry is essential to better understand of the structure of nucleon and also the perturbative and nonperturbative mechanisms for sea quark generation. Actually, the nature and dynamical origins of this asymmetry have always been an interesting subject to research both experimentally and theoretically. One of the most powerful models can lead to $ s-\bar s $ asymmetry is the meson-baryon model (MBM). In this work, using a simplified configuration of this model suggested by Pumplin, we calculate the $ s-\bar s $ asymmetry for different values of cutoff parameter $\Lambda$, to study the dependence of model to this parameter and also to estimate the theoretical uncertainty imposed on the results due to its uncertainty. Then, we study the evolution of distributions obtained both at next-to-leading order (NLO) and next-to-next-to-leading order (NNLO) using different evolution schemes. It is shown that the evolution of the intrinsic quark distributions from a low initial scale, as suggested by Chang and Pang, is not a good choice at NNLO using variable flavor number scheme (VFNS).