Impact of new measurements of light quarks at hadron colliders

TL;DR

Recent measurements at hadron colliders reveal deviations from existing PDFs, suggesting a need to update the light quark distributions, especially the valence $d_v/u_v$ ratio, based on new collider and fixed target data.

Contribution

This study evaluates the impact of recent collider measurements on light quark PDFs and highlights the importance of including these data in future global analyses.

Findings

Deviations favor a larger valence $d_v/u_v$ ratio.

Impact is similar across different boson propagators and energies.

Tension mainly arises from NMC and NuSea deep inelastic scattering data.

Abstract

Recently a series of new measurements with both the neutral and charge current Drell--Yan processes have been performed at hadron colliders, showing deviations from the predictions of the current parton distribution functions (PDFs). In this article, the impact of these new measurements is studied by using their results to update the PDFs. Although these new measurements correspond to different boson propagators and colliding energies, they are found to have a similar impact to the light quark parton distributions with the momentum fraction $x$ around 0.1. It manifests that the deviations are consistent with each other and favor a larger valence $d_v/u_v$ ratio than the modern PDF predictions. Further study indicates that such tension arises dominantly from the deep inelastic scattering measurements of NMC and the fixed target experiments of NuSea, both of which play pivotal roles in detecting the relative $u$ and $d$ type quark contributions for modern PDFs. According to the conclusions of the impact study, it would be essential to include these new measurements into the complete PDF global analysis in the future.