XXVIII International Workshop on Deep Inelastic Scattering and Related Subjects

Measurements of Jet Cross Sections in proton-proton Collisions at STAR

24 Mar 2020, 14:30

18m

Brooklyn, NY

Structure Functions and Parton Densities Structure function and parton densities

Speaker

Zilong Chang (Brookhaven National Laboratory)

Description

Jets, clusters of collimated particles, produced from parton scatterings in high energy
proton-proton collisions are an effective tool to study the internal proton structure. At center of mass
energies of $\sqrt{s}=$ 200 and 510 GeV, jet production is dominated by the quark-gluon, $qg$ and
gluon-gluon, $gg$, scattering processes. The STAR experiment at the Relativistic Heavy Ion Collider (RHIC) has measured a series of jet asymmetries in the pseudo-rapidity range, $-1<\eta <2$, in longitudinally polarized $pp$ collisions to constrain the gluon polarization in the proton. Similarly jet cross-section measurements for unpolarized $pp$ collisions are an excellent probe to constrain the unpolarized gluon distribution. In this talk the STAR jet cross-section measurements in two $\eta$ ranges, $|\eta |<0.5$ and $0.5<|\eta |<0.9$ for $510$ GeV $pp$ data are presented. The techniques used in this analysis, such as the underlying event correction to the jet energy and the unfolding procedure that maps the detector-level jet quantities to physics quantities at the particle level are described. Their impact on the unpolarized proton parton distribution functions through re-weighting is discussed.