Speaker
Description
While the unpolarized valence quark ($d$ and $u$) distributions 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, are sensitive to the $\bar{d}/\bar{u}$ ratio at leading order at a large $Q^2$ set by the $W$ mass. This talk will discuss the recently published $W$ and $Z/\gamma^*$ cross section measurements via lepton-decay tagging, using the STAR $pp$ collision data at a center-of-mass energy of $\sqrt{s} = 510\,\mathrm{GeV}$ collected during the years 2011-2013, corresponding to an integrated luminosity of $350\,\mathrm{pb^{-1}}$. A status update will be given on an analysis based on an additional data set at $\sqrt{s} = 510\,\mathrm{GeV}$ collected in 2017, corresponding to an integrated luminosity of $350\,\mathrm{pb^{-1}}$.
