Measurements of $W$ and $Z/\gamma^*$ cross sections and their ratios in $pp$ collisions at STAR

TL;DR

This paper reports measurements of $W$ and $Z$ boson production cross sections in proton-proton collisions at STAR, providing insights into sea quark distributions and their ratios at high energy scales.

Contribution

It presents new experimental data on $W$ and $Z$ cross sections at STAR, improving constraints on sea quark asymmetries in the proton.

Findings

Measured $W$ and $Z$ cross sections at $ oot s = 500/510$ GeV.

Provided data to constrain $ar{d}/ar{u}$ ratios.

Enhanced understanding of sea quark distributions in proton.

Abstract

While the unpolarized parton distribution functions of the valence quarks ($d$ and $u$) are well determined from DIS experiments, the sea quark counterparts, $\bar{d}$ and $\bar{u}$, are much less constrained, in particular, near the valence region. Measurements of $W^+/W^-$ production ratio in $pp$ collider experiments, such as the STAR experiment at RHIC, can probe the $\bar{d}/\bar{u}$ ratio at a large $Q^2$ set by the $W$ mass. These proceedings will discuss recent results of $W$ and $Z$ cross-section measurements using the STAR $pp$ collision data at a center-of-mass energy of $\sqrt{s} = 500/510\;\mathrm{GeV}$ collected in 2011, 2012, 2013 and 2017.