Observation of $D^0$ meson nuclear modifications in Au+Au collisions at $\sqrt{s_{_{\mathrm{NN}}}}$ = 200 GeV

TL;DR

This paper reports the first measurement of $D^0$ meson production in Au+Au collisions at 200 GeV, showing suppression at high transverse momentum and enhancement at intermediate $p_T$, indicating charm quark energy loss and medium interactions.

Contribution

It provides the first experimental observation of charm-hadron suppression and enhancement patterns in heavy-ion collisions at RHIC energies, highlighting charm-medium interactions.

Findings

$D^0$ yields are suppressed at high $p_T$ in central Au+Au collisions.

An enhancement of $D^0$ yields is observed at intermediate $p_T$.

Charm quarks experience significant energy loss in the quark-gluon plasma.

Abstract

We report the first measurement of charmed-hadron ($D^0$) production via the hadronic decay channel ($D^0\rightarrow K^- + \pi^+$) in Au+Au collisions at $\sqrt{s_{_{\mathrm{NN}}}}$ = 200\,GeV with the STAR experiment. The charm production cross-section per nucleon-nucleon collision at mid-rapidity scales with the number of binary collisions, $N_{bin}$, from $p$+$p$ to central Au+Au collisions. The $D^0$ meson yields in central Au+Au collisions are strongly suppressed compared to those in $p$+$p$ scaled by $N_{bin}$, for transverse momenta $p_{T}>3$ GeV/$c$, demonstrating significant energy loss of charm quarks in the hot and dense medium. An enhancement at intermediate $p_{T}$ is also observed. Model calculations including strong charm-medium interactions and coalescence hadronization describe our measurements.