# Parton distributions from nonlocal chiral SU(3) effective theory: Flavor asymmetries

## TL;DR

This paper uses a nonlocal chiral SU(3) effective theory to calculate flavor asymmetries in the proton, aligning well with experimental data and predicting specific asymmetry behaviors for strange and light antiquarks.

## Contribution

It introduces a novel nonlocal chiral effective theory approach to compute flavor asymmetries in the proton, constrained by baryon production data.

## Key findings

- The $ar{d}-ar{u}$ asymmetry matches Fermilab E866 results.
- The $s-ar{s}$ asymmetry is positive at $x>0$ with specific magnitude.
- No sign change in asymmetry at large $x$ observed.

## Abstract

Using recently derived results for one-loop hadronic splitting functions from a nonlocal implementation of chiral effective theory, we study the contributions from pseudoscalar meson loops to flavor asymmetries in the proton. Constraining the parameters of the regulating functions by inclusive production of $n$, $\Delta^{++}$, $\Lambda$ and $\Sigma^{*+}$ baryons in $pp$ collisions, we compute the shape of the light antiquark asymmetry $\bar{d}-\bar{u}$ in the proton and the strange asymmetry $s-\bar{s}$ in the nucleon sea. With these constraints, the magnitude of the $\bar{d}-\bar{u}$ asymmetry is found to be compatible with that extracted from the Fermilab E866 Drell-Yan measurement, with no indication of a sign change at large values of $x$, and an integrated value in the range $\langle \bar d-\bar u \rangle \approx 0.09-0.17$. The $s-\bar s$ asymmetry is predicted to be positive at $x > 0$, with compensating negative contributions at $x=0$, and an integrated $x$-weighted moment in the range $\langle x (s-\bar s) \rangle \approx (0.9-2.5) \times 10^{-3}$.