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

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, divided by the number of binary nucleon-nucleon collisions, in root S-NN = 200 GeV Au+Au collisions to p+p collisions (R-AA), or in central to peripheral Au+Au collisions (R-CP). We find the bottom-decay electron R-AA and R-CP to be significantly higher than those 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 evidence of mass ordering of charm and bottom quark energy loss when traversing through the strongly coupled medium created in heavy-ion collisions.

Automated summary

This study investigates the energy loss of charm and bottom quarks in the strongly interacting medium created in heavy-ion collisions. The experimental results reveal that the energy loss of bottom quarks is higher than that of charm quarks. Model calculations show that the assumption of mass-dependent parton energy loss is consistent with the measured data. These observations provide evidence of mass ordering of energy loss for charm and bottom quarks when traversing through the strongly coupled medium created in heavy-ion collisions.