  High transverse momentum (P_T) QCD scattering processes are regarded as a
valuable tool to study the medium produced in heavy-ion collisions, as due to
uncertainty arguments their cross section should be calculable independent of
medium properties whereas the medium then modifies only the final state partons
emerging from a hard vertex. With the heavy-ion physics program at the CERN LHC
imminent, the attention of high P_T physics in heavy ion collisions is shifting
from the observation of hard single hadrons to fully reconstructed jets.
However, the presence of a background medium at low P_T complicates jet-finding
as compared to p-p collisions. Monte-Carlo (MC) codes designed to simulate the
evolution of parton showers evolving into hadron jets are valuable tools to
understand the complicated interplay between the medium modification of the jet
and the bias introduced by a specific jet-finding scheme. However, such codes
also use a set of approximations which needs to be tested against the better
understood single high P_T hadron observables. In this paper, I review the
ideas underlying the MC code YaJEM (Yet another Jet Energy-loss Model) and
present some of the results obtained with the code.
