The partonic energy loss has been calculated taking both the hard and soft
contributions for all the 2→2 processes, revealing the importance of the
individual channels. Cancellation of the intermediate separation scale has been
exhibited. Subtleties related to the identical final state partons have
properly been taken into account. The estimated collisional loss is compared
with its radiative counter part. We show that there exists a critical energy
(Ec) below which the collisional loss is more than its radiative
counterpart. In addition, we present closed form formulas for both the
collision probabilities and the stopping power (dE/dx)Comment: revised version, section added, 9pages with 5 figure