Constraining Sea Quark Distributions Through $W^{\pm}$ Cross Section Ratios Measured at STAR

29 Apr 2015, 11:35


WG1 Structure Functions and Parton Densities WG1 Structure Functions and Parton Densities


Dr Matthew Posik (Temple University)


Over the past several years the STAR experiment at RHIC has been contributing to our understanding of the proton structure. Through proton-proton collisions, STAR is well equipped to measure the e$^{\pm}$ leptonic decays of $W^{\pm}$ bosons in the mid-rapidity region (-1.1 $\le \eta \le $ 1.1) at $\sqrt{s}$ = 500/510 GeV. The $W$ cross section ratio ($W^+/W^-$) is sensitive to unpolarized $u$, $d$, $\bar{u}$, and $\bar{d}$ quark distributions. At these kinematics STAR is able to measure the quark distributions near Bjorken-x of 0.1. The RHIC runs in 2012 and 2013 at $\sqrt{s}$ = 500/510 GeV saw a significant increase in delivered luminosity from previous years. This resulted in using data samples of about 80 and 250 pb$^{-1}$ of integrated luminosity, respectively. The increased statistics will lead to a higher precision measurement of the $W^{+}/W^{-}$ cross section ratio as well as its $\eta$ dependence at mid-rapidity. Presented here is an update of the $W$ cross section ratio analysis from the STAR 2012 and 2013 runs.

Primary author

Dr Matthew Posik (Temple University)

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