Abstracts for Light Cone 2017 (Gluon Saturation / TSSA)

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Jet like azimuthal correlations in p+p and p+Au collisions at STAR at forward rapidity
Mriganka Mouli Mondal (for STAR Collaboration)

For very low Bjorken's x when parton density goes beyond some energy limit, gluons in nucleus/nuclei expected to transit to a saturation regime. So far no clear experimental observation on onset of gluon saturation is being made. Observables at forward rapidity at STAR in prton nuclei collisions probes gluons at very small x where gluon density expected to reach the saturation regime. Previous results on di-pion azimuthal correlations on d+Au in STAR showed the hints of saturation. The azimthal correlations appearing in hard scatterings is expected to get modified due to multiple gluon scatterings in proton nuclei collisions which is interesting to scan over rapidity and transverse scale of interactions. During 2015 RHIC run, Solenoidal Tracker At RHIC (STAR) with the forward electromagnetic calorimeter, the Forward Meson Spectrometer (FMS), recorded data in {\it p+p}, {\it p+Al} and {\it p+Au} collisions at $\sqrt{s}$ = 200GeV. Psedo-rapidity($\eta$) coverage for calorimeters in STAR spans from 4.0 to -1.0 where FMS contributing in $\eta$=[2.5,4.0] and other central calorimeters in $\eta$=[-1.0,2.0]. Anti-kt clustering algorithm is used to find jets using the energies in the calorimeters. The status of azimuthal di-jet like correlations for the data in this unique acceptance would be presented.

Transverse single spin asymmetries ($A_N$) at large Feynman x ($x_{F}$) in the STAR experiment at RHIC
Mriganka Mouli Mondal (for STAR Collaboration)

Large Traverse Single Spin Asymmetries ($A_N$), i.e, left right asymmetries for particle production with respect to the proton's transverse spin polarization direction is a well known observation. This large $A_N$ can be described by phenomenological models in TMD like Sivers and Collins effects, or in higher twist contributions in the initial and final states. We have to go beyond inclusive measurements and to use probes like jets and direct photons to access Sivers contributions, while to use fragments in jets for accounting Collins contributions.
STAR forward electromagnetic calorimeter, Forward Meson Spectrometer (FMS), detects $\pi^0$, $\eta$ mesons at high $x_{F}$ where $A_N$ known to be large. FMS upgradation with installations of pre-shower and post-shower detectors in 2015-2017, FMS can detect direct photons and Drell Yan(DY), and thereby, it has potential to discover sign change for DY. Observation of large $A_N$ for isolated $\pi^0$ is still a puzzle in the STAR experiment. In this context we will take the advantage of large acceptance of FMS to reconstruct electromagnetic jets and will show $A_N$ for electromagnetic jets, neutral pions and Collins measurements for $\pi^0$'s in jets from $p\uparrow$ + $p\uparrow$ collisions at $\sqrt{s}$ = 500 GeV.