Energy loss of a heavy quark produced in a finite size medium

We study the medium-induced energy loss –ΔE0(Lp) suffered by a heavy quark produced at initial time in a quark-gluon plasma, and escaping the plasma after travelling the distance Lp. The heavy quark is treated classically, and within the same framework –ΔE0(Lp) consistently includes: the loss from standard collisional processes, initial bremsstrahlung due to the sudden acceleration of the quark, and transition radiation. The radiative loss induced by rescatterings –ΔErad(Lp) is not included in our study. For a ultrarelativistic heavy quark with momentum p 10 GeV, and for a finite plasma with Lp 5 fm, the loss –ΔE0(Lp) is strongly suppressed compared to the stationary collisional contribution –ΔEcoll(Lp) ∝ Lp. Our results support that –ΔErad is the dominant contribution to the heavy quark energy loss (at least for Lp 5 fm), as indeed assumed in most of jet-quenching analyses. However they might raise some question concerning the RHIC data on large p⊥ electron spectra.