Extracting $W$ Single Spin Asymmetry in Longitudinally Polarized $pp$ Collisions at PHENIX forward arms

The parity-violating asymmetry $A_L$ in the production of $W$ bosons in $p+p$ collisions at $\sqrt{s}$ = 510 GeV is sensitive to the polarization of light quarks and anti-quarks in the proton. However, identifying the lepton from the decay of the $W$ is challenging due to a great background of hadronic processes. In the forward and backward hemispheres of PHENIX at RHIC, the muon spectrometers have been recently upgraded in order to provide additional trigger and tracking information to suppress those backgrounds. One of those upgrades is the Forward Vertex (FVTX) detector, a silicon-strip tracker. In 2013, PHENIX collected approximately 240 pb$^{-1}$ of polarized $p+p$ collisions at $\sqrt{s}$ = 510 GeV with a beam polarization of 52$\%$. The ability of the FVTX to improve the $W$ signal will be reviewed, and progress on analysis of real data in the RHIC 2013 run will be discussed.