Jet measurements in polarized p+p collisions at STAR at RHIC

29 Apr 2015, 14:25


WG6 Spin Physics WG6 Spin Physics


Dr Xuan Li (Temple University)


Inclusive jet- and di-jet productions in polarized p+p collisions at $\sqrt{s} = 200$ GeV and $\sqrt{s} = 500$ GeV provide powerful probes to study gluons inside the proton. Inclusive jet production is sensitive to the integral of the gluon distribution over a broad range of $x$. Di-jet production provides better sensitivity to $x$ dependence of gluons. The Solenoidal Tracker at RHIC (STAR) has the capability, with nearly full azimuthal ($2\pi$) coverage, to reconstruct jets at mid-rapidity ($|\eta| < 1$). Different x regions of gluons inside the proton can be accessed by the STAR experiment through sampling different center of mass energies and pseudorapidities. Inclusive jet and di-jet cross section measurements at STAR have been found to be in good agreement with NLO pQCD calculations taking into account effects of hadronization and underlying events. The latest STAR inclusive jet double-spin asymmetry $A_{LL}$ measured in 200 GeV p+p collisions provides the first evidence of non-zero gluon contribution to the proton spin. Selected measurements of inclusive jet and di-jet cross-sections and longitudinal double-spin asymmetries will be presented; including the new inclusive jet cross section using the anti-$k_{T}$ algorithm with potential insights into PDFs, and the new inclusive jet $A_{LL}$ measurements in 510 GeV p+p collisions which shows consistent $x_{T}$ scaling with the 200 GeV result. In addition, projections for the inclusive jet and di-jet double-spin asymmetries in longitudinal polarized p+p collisions from the latest and future RHIC runs will be discussed.

Primary author

Dr Xuan Li (Temple University)

Presentation Materials