  Jets are an important tool to probe the hot, dense medium produced in
ultra-relativistic heavy-ion collisions. At the collision energies available at
the Large Hadron Collider (LHC), there is copious production of hard processes,
such that high p_T jets may be differentiated from the heavy-ion underlying
event. The multipurpose Compact Muon Solenoid (CMS) detector is well designed
to measure hard scattering processes with its high quality calorimeters and
high precision silicon tracker. Jet quenching has been studied in CMS in PbPb
collisions at sqrt(s_NN)= 2.76 TeV. As a function of centrality, dijet events
with a high p_T leading jet were found to have an increasing momentum imbalance
that was significantly larger than predicted by simulations. The angular
distribution of jet fragmentation products has been explored by associating
charged tracks with the jets measured in the calorimeters. By projecting the
momenta of charged tracks onto the leading jet axis it is shown that the
apparent momentum imbalance of the leading dijet pair can be recovered if low
p_T tracks are considered. A large fraction of the balancing momentum carried
by these soft particles is radiated at large angle relative to the jets.
