Dense-Medium Modifications to Jet-Induced Hadron Pair Distributions in $\mathrm{Au}+\mathrm{Au}$ Collisions at $\sqrt{s_{NN}}=200\mathrm{GeV}$

Azimuthal correlations of jet-induced high-$p_T$ charged hadron pairs are studied at midrapidity in $\mathrm{Au}+\mathrm{Au}$ collisions at $\sqrt{s_{NN}}=200\mathrm{GeV}$. The distribution of jet-associated partner hadrons ($1.0<p_T<2.5\mathrm{GeV}/c$) per trigger hadron ($2.5<p_T<4.0\mathrm{GeV}/c$) is found to vary with collision centrality, in both shape and yield, indicating a significant effect of the nuclear collision medium on the jet fragmentation process.

Figure 1

Correlation functions, $C(\Delta \varphi )$, for pairs of charged hadrons with $2.5\mathrm{GeV}/c<p_T^A<4.0\mathrm{GeV}/c$ and $1.0\mathrm{GeV}/c<p_T^B<2.5\mathrm{GeV}/c$ in different bins of collision centrality from the most central (a) 0%–5% to the most peripheral (f) 60%–90%. The solid bands indicate the estimate of the background pair component (see text) within one unit of its systematic error.

Figure 2

Jet-pair distributions $d{N}_{(\mathrm{di})\mathrm{jet}}^{AB}/d(\Delta \varphi )$ for different centralities, normalized per trigger particle. The shaded bands indicate the systematic error associated with the determination of $\Delta {\varphi }_{\min }$. The dashed (solid) curves are the distributions that would result from increasing (decreasing) $⟨v_2^A{v}_2^B⟩$ by one unit of the systematic error; the dotted curve would result from decreasing by two units.

Figure 3

(a) Associated yields for near- and awayside peaks in the jet-pair distribution, and (b) widths (rms) of the peaks in the full $0–2\pi$ distributions; plotted versus the mean number of participating nucleons for each event sample. Triangles show results from 0%–20% central $d+\mathrm{Au}$ collisions at the same $\sqrt{s_{NN}}$ [23]. Bars show statistical errors, shaded bands systematic.