# Strange quark-antiquark asymmetry of nucleon sea from $\Lambda/\bar\Lambda$ polarization

## TL;DR

This paper investigates how the asymmetry between strange and antistrange quarks in the nucleon sea influences the polarization of Lambda and anti-Lambda particles, providing evidence for intrinsic strange quark asymmetry through semi-inclusive deep inelastic scattering data.

## Contribution

The study introduces a realistic model of quark to Lambda fragmentation that amplifies the strange-antistrange asymmetry effect, aligning theoretical predictions with experimental observations.

## Key findings

- Qualitative agreement with experimental polarization data
- Evidence supporting intrinsic strange sea and asymmetry
- Lambda polarization as a probe for nucleon sea properties

## Abstract

Distinctions between quark to $\Lambda$ and $\bar\Lambda$ longitudinal spin transfers in the semi-inclusive deep inelastic scattering process were observed by the E665 and COMPASS Collaborations. There are suggestions that the difference between $\Lambda$ and $\bar\Lambda$ production is related to the asymmetric strange-antistrange distribution inside the nucleon. However, previous calculations are still too small to explain the experimental data. From a realistic consideration of quark to $\Lambda$ fragmentation due to different flavors, we investigate the strange quark contribution for $\Lambda$ production and polarization. We find that the strange quark-antiquark asymmetry of the nucleon sea can be amplified into an observable quantity from the difference between $\Lambda$ and $\bar\Lambda$ polarizations after taking into account the larger probability of the $\Lambda$ produced from the $s$ quark fragmentation process compared to that from the $u$ or $d$ quark. The qualitative agreement between our calculation and the experimental data supports the existence of the intrinsic strange sea and the strange-antistrange asymmetry. Thus the polarization of $\Lambda/\bar\Lambda$ does open a new window to probe the nucleon sea properties, especially the strange content and its quark-antiquark asymmetry.