  We present the preliminary results of measurements of single spin
asymmetries, $A_L$ for $W^\pm$ boson production in longitudinally polarized p+p
collisions at $\sqrt{s}=510$ GeV and measurements of cross section ratios,
$\sigma _{W^+} / \sigma _{W^-}$, for $W^+,W^-$ boson production in $p+p$
collisions at $\sqrt{s}$ = 500 and 510 GeV. The asymmetry measurements are
based on 246.2 pb$^{-1}$ of data taken in the RHIC 2013 run and the cross
section ratio measurements are based on 102 pb$^{-1}$ of data taken during RHIC
2011 and 2012 runs by the STAR experiment. While the asymmetry results are
shown as a function of the decay lepton pseudorapidity, $\eta_e$, the cross
section results are shown as a function of both $\eta_e$ and W boson rapidity,
$y_W$ in the mid-rapidity region ($|\eta_e|<1$). At this kinematics, $W^\pm$
single spin asymmetries provide a theoretically clean probe of the proton's
polarized quark and antiquark distributions and the W cross section ratio
provides sensitivity to unpolarized sea quark distributions at the scale of the
W mass. The asymmetry results are consistent with recently published STAR
$A^{W^\pm}_L$ results based on the data collected during RHIC 2011 and 2012
runs which showed a preference for a sizable, positive up antiquark
polarization in the range $0.05 < x < 0.2$. The new preliminary results can be
considered as the most precise results of $A^{W^\pm}_L$ in the world to date,
with uncertainties reduced by 40\% in comparison to the published results.
