Measurement of $\gamma$+jet and $\pi^{0}$+jet in central Au+Au collisions at $\sqrt{s_{\mathrm{NN}}}$ = 200 GeV with the STAR experiment

TL;DR

This study measures charged jet yields recoiling from direct-photon and neutral pion triggers in central gold-gold collisions at 200 GeV, providing insights into jet quenching and parton energy loss in the quark-gluon plasma.

Contribution

It introduces a semi-inclusive method using a mixed-event technique to accurately measure recoil jets over a broad momentum range in heavy-ion collisions.

Findings

Recoil jet yields are corrected for background using a novel mixed-event technique.

Jet R dependence reveals in-medium parton energy loss characteristics.

Results contribute to understanding jet quenching at RHIC energies.

Abstract

We present the semi-inclusive measurement of charged jets recoiling from direct-photon and $\pi^{0}$ triggers in central Au+Au collisions at $\sqrt{s_{\mathrm {NN}}}$ = 200 GeV, using a dataset with integrated luminosity 13 $\mathrm {nb^{-1}}$ recorded by the STAR experiment in 2014. The photon and $\pi^{0}$ triggers are selected within transverse energy ($\rm E_\mathrm{T}^\mathrm{trig}$) between 9 GeV and 20 GeV. Charged jets are reconstructed with the anti-$k_{\mathrm{T}}$ algorithm with resolution parameters R = 0.2 and 0.5. A Mixed-Event technique developed previously by STAR is used to correct the recoil jet yield for uncorrelated background, enabling recoil jet measurements over a broad $\rm p_{T,jet}$ range. We report fully corrected charged-jet yields recoiling from direct-photon and $\pi^{0}$ triggers for the above two jet radii and also discuss the jet R dependence of in-medium parton energy loss at the top RHIC energy.