Energy loss of a heavy quark in the quark-gluon plasma

The energy loss dE/dx for a heavy quark propagating through a quark-gluon plasma is calculated to leading order in the QCD coupling constant. Simple formulas for dE/dx are obtained in the regions EMQ²T and EMQ²T, where MQ is the mass of the heavy quark and T is the temperature. The crossover energy between the two regions is determined to be approximately 1.8MQ²T. Under conditions relevant to ultrarelativistic heavy-ion collisions, charm quarks and bottom quarks lie on opposite sides of the crossover energy and therefore experience significantly different energy losses.