Evidence of Mass Ordering of Charm and Bottom Quark Energy Loss in Au+Au Collisions at RHIC

Abstract

Partons traversing the strongly interacting medium produced in heavy-ion collisions are expected to lose energy depending on their color charge and mass. We measure the nuclear modification factors for charm- and bottom-decay electrons, defined as the ratio of yields, scaled by the number of binary nucleon-nucleon collisions, in $\sqrt{s_{\mathrm{NN}}}$ = 200 GeV Au+Au collisions to $p$+$p$ collisions ($R_{\mathrm{AA}}$), or in central to peripheral Au+Au collisions ($R_{\mathrm{CP}}$). We find the bottom-decay electron $R_{\mathrm{AA}}$ and $R_{\mathrm{CP}}$ to be significantly higher than that of charm-decay electrons. Model calculations including mass-dependent parton energy loss in a strongly coupled medium are consistent with the measured data. These observations provide clear evidence of mass ordering of charm and bottom quark energy loss when traversing through the strongly coupled medium created in heavy-ion collisions.

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• The Present and Future of QCD
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• Probing the mass effect of heavy quark jets in high-energy nuclear collisions
• Reexamining charm versus bottom quark energy loss inside a color-deconfined medium
• Charm- and Bottom-Quark Production in Au$+$Au Collisions at $\sqrt{s_{{}_{NN}}}$ = 200 GeV
• Production of leptons from decay of heavy-flavor hadrons in high-energy nuclear collisions