XXVIII International Workshop on Deep Inelastic Scattering and Related Subjects

Longitudinal double-spin asymmetries of inclusive jet and di-jet production at STAR

24 Mar 2020, 11:40

20m

Brooklyn, NY

Contributed Talk Spin Physics Spin Physics

Speaker

Maria Zurek (Lawrence Berkeley National Laboratory)

Description

The Solenoidal Tracker at the Relativistic Heavy Ion Collider (STAR) experiment probes the gluon helicity distribution $\mathrm{\Delta }G(x)$ using collisions of longitudinally polarized protons at $\sqrt{s}=$ 200 GeV and $\sqrt{s}=$ 510 GeV. Access to $\mathrm{\Delta }G(x)$ is possible through the double spin asymmetries $A_{LL}$ in gluon-dominated hard scattering processes of inclusive jet and di-jet production.

Previously published results on inclusive jet processes at $\sqrt{s}=$ 200 GeV and $|{\eta }_{\mathrm{jet}}|<1$ are based on data collected in 2009, which correspond to an integrated luminosity ($L$) of 20 pb${}^{-1}$ with an average beam polarization ($P$) of 57%. When included in perturbative QCD analysis of global data, they provide evidence for positive gluon polarization for a momentum fraction $x>0.05$ at a hard perturbative scale $Q^2=10$ GeV${}^2$. Additional data were collected in 2015 with an approximately twice larger figure of merit $\left(L{P}^4\right)$. This contribution will cover the status of the analysis of 2015 inclusive jet and di-jet data, as well as, the jet measurements based on the most recent high-luminosity 510 GeV data collected in 2013, which will further constrain $\mathrm{\Delta }G(x)$ at lower $x$.