Semi-inclusive direct photon+jet and $\pi^{0}$+jet correlations measured in $p+p$ and central Au+Au collisions at $\sqrt{s_\mathrm{NN}} = 200$ GeV

Author:

STAR Collaboration

Keyword:

Nuclear Experiment, Nuclear Experiment (nucl-ex), High Energy Physics - Experiment (hep-ex), High Energy Physics - Phenomenology (hep-ph), Nuclear Theory (nucl-th)

journal:

date:

2023-08-30 16:00:00

Abstract

The STAR experiment at RHIC reports new measurements of jet quenching based on the semi-inclusive distribution of charged-particle jets recoiling from direct photon ($\gamma_{\rm dir}$) and neutral pion ($\pi^{0}$) triggers in $p+p$ and central Au+Au collisions at $\sqrt{s_\mathrm{NN}} = 200$ GeV, for triggers in the range $9< E_{T}^{\rm trig}<20$ GeV. The datasets have integrated luminosities of 3.9 $\rm nb^{-1}$ for Au+Au and 23 $\rm pb^{-1}$ for $p+p$ collisions. Jets are reconstructed using the anti-$k_{\rm T}$ algorithm with resolution parameters $R=0.2$ and 0.5. The large uncorrelated jet background in central Au+Au collisions is corrected using a mixed-event approach, which enables precise charged-particle jet measurements at low transverse momentum $p_{\rm T, jet}^{\rm ch}$ and large $R$. Recoil-jet distributions are reported in the range $p_{\rm T, jet}^{\rm ch}<25$ GeV. Comparison of the distributions measured in $p+p$ and Au+Au collisions reveals strong medium-induced jet yield suppression for $R=0.2$, with markedly less suppression for $R=0.5$. These data provide new insight into the mechanisms underlying jet quenching, and the angular dependence of medium-induced jet-energy transport.

PDF: Semi-inclusive direct photon+jet and $\pi^{0}$+jet correlations measured in $p+p$ and central Au+Au collisions at $\sqrt{s_\mathrm{NN}} = 200$ GeV.pdf