Measurement of the Transverse Single-Spin Asymmetries for $\pi^{0}$ and Electromagnetic Jets at forward rapidities at STAR

Large transverse single-spin asymmetries ($A_N$) have been observed for forward inclusive hadron production in $p+p$ collisions at various experiments. In the collinear perturbative scattering picture, twist-3 multi-parton correlations can give rise to such an asymmetry. There can also be a spin-dependent hadronization process which can create transverse asymmetries in the twist-3 fragmentation formalism. The observed $A_N$ may involve contributions from both processes. These can be disentangled by studying asymmetries for jets, direct photons and jet-fragments. The STAR Forward Meson Spectrometer, a Pb-glass electromagnetic calorimeter covering the pseudo-rapidity ($\eta$) range 2.6-4.2 and full azimuth, can detect photons, neutral pions and $\eta$ mesons. For the current run in the year 2015, installation of the Forward Pre-shower Detector opens a new capability of identifying direct photon events. We are measuring $A_N$ for $\pi^{0}$ and electromagnetic(EM) jets reconstructed from photons in the FMS in $p+p$ collisions at $\sqrt{s}$ = 500 GeV that were recorded during the 2011 RHIC run. We report, here, $A_N$ for forward EM-jets and its sensitivity to the event topology of having a coincedence EM-jet at midrapidity.