Inclusive cross section and correlations of fully reconstructed jets in 200 GEV Au+Au and p+p collisions

TL;DR

Fully reconstructed jets provide an unbiased framework to study jet quenching in heavy-ion collisions, addressing biases of hadron-based observables. The authors measure inclusive jet cross sections, R_AA, and hadron–jet correlations in 200 GeV p+p and central Au+Au using seedless jet finding and robust background subtraction across $R=0.2$ and $R=0.4$. They find near-unity $R_{AA}^{\text{jet}}$ for $R=0.4$ but significant jet broadening for $R=0.2$, with hadron–jet correlations showing energy redistribution in the medium. These results demonstrate the feasibility and value of fully reconstructed jets for quantifying jet quenching and energy flow in the quark-gluon plasma.

Abstract

We present an experimental study of full jet reconstruction in the high multiplicity environment of heavy ion collisions, utilizing 200 GeV p+p and central Au+Au data measured by STAR. Inclusive differential jet production cross sections and ratios are reported, as well as high-pT hadron-jet coincidences.

Figures (3)

• Figure 1: Cross sections for inclusive jet production in p + p ( left) and Au + Au collisions ( right) at $\sqrt{s_{NN}}=200~$GeV ($k_{T}$ and anti-$k_{T}$, R = 0.2 and 0.4). Error bands described in the text. Published p + p data are from Ref. bib:star_jetpaper.
• Figure 2: Ratios of inclusive jet cross sections in p + p and Au + Au collisions at $\sqrt{s_{NN}}=200$ GeV ($k_{T}$ and anti-$k_{T}$, R = 0.2 and 0.4). Left: Jet $R_{AA}$. Right: Ratio of cross sections $R=0.2/R=0.4$ for each system.
• Figure 3: Ratios of hadron--jet conditional yields for three selections of the leading particle of the recoil jet, reconstructed in 10% most central Au + Au collisions and in p + p collisions. Jets were reconstructed with anti-$k_{T}$ algorithm with $R=0.4$ and correlated at $\Delta\phi \approx \pi$ with a leading high tower trigger cluster (dominated by $\pi^{0}$).