Measurement of medium-induced modification of jet yield and acoplanarity using semi-inclusive ${\gamma }_{\text{dir}}$+jet and ${\pi }^0$+jet distributions in $p$+$p$ and central Au+Au collisions at $\sqrt{s_{NN}}=200$ GeV by STAR

Abstract

The STAR collaboration presents measurements of semi-inclusive distributions of charged jets recoiling from high transverse energy ($E_{\text{T}}$) direct photon and ${\pi }^0$ triggers in $p$+$p$ and central Au+Au collisions at $\sqrt{s_{\text{NN}}}=200$ GeV. Jets are reconstructed from charged particles using the anti-$k_{\text{T}}$ algorithm with jet resolution parameters $R=0.2$ and 0.5. The large uncorrelated background in central Au+Au collisions is corrected using a mixed-event technique. This enables a jet measurement extending to low transverse momentum and large $R$ with well-controlled systematic uncertainties. We present measurements of the jet $R$ dependence of suppression, intra-jet broadening, and acoplanarity of ${\pi }^0$+jet and ${\gamma }_{\text{dir}}$+jet for trigger $E_{\text{T}}$ ($E_{\text{T}}^{\text{trig}}$) between $9-20$ GeV.

Proceedings updated for the International Conference on High Energy Physics 2022