We present measurements of azimuthal correlations of charged hadron pairs in $\sqrt{s_{\mathit{NN}}}=200$ GeV $\mathrm{Au}+\mathrm{Au}$ collisions for the trigger and associated particle transverse-momentum ranges of $1<p_T^t<10\mathrm{GeV}/c$ and $0.5<p_T^a<10\mathrm{GeV}/c$. After subtraction of an underlying event using a model that includes higher-order azimuthal anisotropy $v_2, v_3$, and $v_4$, the away-side yield of the highest trigger-$p_T$($p_T^t>4\mathrm{GeV}/c$) correlations is suppressed compared with that of correlations measured in $p+p$ collisions. At the lowest associated particle $p_T$($0.5<p_T^a<1\mathrm{GeV}/c$), the away-side shape and yield are modified relative to those in $p+p$ collisions. These observations are consistent with the scenario of radiative-jet energy loss. For the low-$p_T$ trigger correlations ($2<p_T^t<4\mathrm{GeV}/c$), a finite away-side yield exists and we explore the dependence of the shape of the away-side within the context of an underlying-event model. Correlations are also studied differentially versus event-plane angle ${\mathrm{\Psi }}_2$ and ${\mathrm{\Psi }}_3$. The angular correlations show an asymmetry when selecting the sign of the difference between the trigger-particle azimuthal angle and the ${\mathrm{\Psi }}_2$ event plane. This asymmetry and the measured suppression of the pair yield out-of-plane is consistent with a path-length-dependent energy loss. No ${\mathrm{\Psi }}_3$ dependence can be resolved within experimental uncertainties.

• Received 6 March 2018
• Revised 14 December 2018

DOI:https://doi.org/10.1103/PhysRevC.99.054903

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Published by the American Physical Society