On the shape of the $\bar d-\bar u$ asymmetry

TL;DR

This paper reanalyzes experimental data to investigate the shape of the - asymmetry in the proton, finding that current data support  >  across accessible x values and comparing results with nonperturbative models.

Contribution

It provides a comprehensive global analysis of DIS and Drell-Yan data to constrain the - asymmetry shape at large x, testing nonperturbative model predictions.

Findings

Data support  >  for all accessible x.

The shape of - distribution aligns with certain nonperturbative models.

Upcoming Drell-Yan data can further test these model predictions.

Abstract

Using data from a recent reanalysis of neutron structure functions extracted from inclusive proton and deuteron deep-inelastic scattering (DIS), we re-examine the constraints on the shape of the $\bar d-\bar u$ asymmetry in the proton at large parton momentum fractions $x$. A global analysis of the proton-neutron structure function difference from BCDMS, NMC, SLAC and Jefferson Lab DIS measurements, and of Fermilab Drell-Yan lepton-pair production cross sections, suggests that existing data can be well described with $\bar d > \bar u$ for all values of $x$ currently accessible. We compare the shape of the fitted $\bar d-\bar u$ distributions with expectations from nonperturbative models based on chiral symmetry breaking, which can be tested by upcoming Drell-Yan data from the SeaQuest experiment at larger values of $x$.