Measurement of the transverse Single Spin Asymmetry of Forward Eta   Mesons in $p^{\uparrow}+p$ Collisions in PHENIX
  Polarized $p+p$ collisions provide insight into the structure of the nucleon. $A_N$ of eta mesons at forward rapidities are of particular interest, as asymmetries of other mesons observed both by PHENIX and other experiments show significant deviation from zero in the forward region. Several mechanisms have been proposed that attempt to explain these non-zero asymmetries, and a comparison of different probes may further constrain these models. Therefore, measurements of $A_N$ with inclusive eta mesons at forward rapidities are an important tool toward understanding the underlying mechanism. Using the PHENIX detector at the Relativistic Heavy Ion Collider (RHIC), we study $p^{\uparrow}+p$ collisions. In 2008, the PHENIX experiment collected 5.2 pb$^{-1}$ integrated luminosity in $p^\uparrow+p$ collisions at $\sqrt{s}$ = 200 GeV. The asymmetry analysis of eta mesons at forward rapidity will be discussed. 
David Kleinjan (for the PHENIX collaboration)
nucl-ex