\begin{document}

 

\title{Inclusive Jet Measurements in Longitudinally Polarized proton-proton Collisions at STAR}

\author{

Zilong Chang, for the STAR Collaboration \\

Brookhaven National Laboratory, Upton, NY 11973

}

\date {\today}

\maketitle

 

Jet production in high energy proton-proton ($pp$) collisions is dominated by hard QCD scatterings such as gluon-gluon ($gg$) and quark-gluon ($qg$) scatterings, and therefore an effective tool to probe the internal distribution of gluons in the proton. The STAR Collaboration at Relativistic Heavy Ion Collider (RHIC) is using longitudinally polarized $pp$ collisions at center of mass energies, $\sqrt{s} = $ 200  and 510 GeV, to study the production cross-section and double helicity spin asymmetry, $A_{LL}$, of inclusive jet and di-jet productions. The inclusive jet and di-jet cross-section measurements by STAR at $\sqrt{s} = $ 200 GeV showed the jet cross-section is consistent with next-to-leading-order perturbative QCD calculations after underlying event and hadronic corrections. The STAR 2009 inclusive jet $A_{LL}$ measurement in mid-pseudo-rapidity range, $|\eta| < $ 1.0, at $\sqrt{s} = $ 200 GeV showed the first experimental evidence of an non-zero gluon polarization for Bjorken-$x$, $x > 0.05$. The inclusive jet $A_{LL}$ measurements at $\sqrt{s} = $ 510 GeV allow to explore the gluon polarization at smaller $x \sim 0.02$.  In this talk, I will present the inclusive jet  $A_{LL}$ and cross-section measurements at $\sqrt{s} =$ 510 GeV, the techniques used in the jet analysis including consideration of underlying event effects, and future perspectives related to jet measurements at STAR. 

 

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