Abstract:
The “proton spin crisis”, emerged from an experiment carried out by the European Muon
Collaboration, remains one of the major unsolved problems in nuclear physics. In solving
this mystery, determining the polarized anti-quark parton distribution functions (PDFs)
may hold key. So far the sea anti-quark polarizations have been measured in the polarized
Semi Inclusive Deep Inelastic (SIDIS) experiments and are poorly constrained compared
to the valence quark polarizations due to large uncertainties from fragmentation
functions.
Measurement of parity violating longitudinal single spin asymmetries of W production is a
complementary approach, free from fragmentation uncertainties compared to Semiinclusive Deep Inelastic Scattering measurements, probing the flavor-separated polarized
sea quark distributions in the proton. At mid-rapidity range of |η|<0.35, candidate W±/Z
events are identified through their e± decay channels. In 2013, PHENIX at the Relativistic
Heavy Ion Collider recorded data with an integrated luminosity of ∼146 pb−1 in
longitudinally polarized p+p collisions at √ =510 GeV. The single spin asymmetry results
of the run 2013 will be presented.
