Speaker
Description
The sea quark contribution to nucleon spin is an important piece for a complete understanding of the nucleon spin structure. The production of $W$-bosons in longitudinally polarized $p+p$ collisions at RHIC provides a unique probe for the sea quark polarization, through the parity-violating single-spin asymmetry, $A_L$. At the STAR experiment, the leptonic decay channel $W\rightarrow e\nu$ can be effectively determined with the Electromagnetic Calorimeters and Time Projection Chamber at mid-rapidity. The previous STAR measurements of $A_L$ for $W$ boson from datasets taken in 2011 and 2012, have provided significant constraints on the helicity distribution functions of $\bar{u}$ and $\bar{d}$ quarks. In 2013 the STAR experiment collected an integrated luminosity of $\sim300\,\mathrm{pb^{-1}}$ at $\sqrt{s} = 510\,\mathrm{GeV}$ with an average beam polarization of $\sim56\%$, which is more than three times larger than the total integrated luminosity of previous years. The new preliminary results of $W$-bosons $A_L$ from 2013 data sample will be presented.
