Measurement of Longitudinal Single-Spin Asymmetry for W Boson Production in Polarized p+p Collisions at STAR

{The production of W-bosons in longitudinally polarized p+p collisions at RHIC is an ideal tool to study the spin-flavor structure of the proton at a high momentum scale, $Q\sim M_W$. $W^{-(+)}$ bosons are produced in $\bar u + d(\bar d+u ) $ collisions and can be detected through their leptonic decays, $e^{-}+\bar {\nu_e} (e^{+} + \nu _e)$. The charged lepton can be detected by the Time Projection Chamber $|\eta|< 1.3$ and the Electromagnetic Calorimeters (Barrel $|\eta|< 1.0 $ and EndCap $ 1< \eta< 2$). The parity-violating nature of the weak production process gives rise to large longitudinal single-spin asymmetries, $A_L$. The measurement of $A_L$ of W-bosons as a function of lepton pseudorapidity $\eta_e$ at STAR provides a unique probe to the valence and sea quark helicity distribution for the fractional momentum range of $0.05 < x < 0.2$ .\par In 2013 the STAR experiment collected an integrated luminosity about 250 pb^{-1 }\hspace{2mm} at \hspace{2mm} $\sqrt s $= 510 GeV with an average beam polarization of $\ 53 \%$. The preliminary results of W-bosons $A_{L}$ from 2013 data sample will be presented.}