Jet quenching
  High-pt particles produced in nucleus-nucleus collisions constitute a powerful tool to study the medium properties. The energy loss resulting from the propagation of these particles in the produced medium translates into a suppression of the high-pt yields. These effects are usually associated to medium-induced gluon radiation which, in turn, predicts a broadening of the jet-like signals. Both the energy loss and the jet broadening are expected to increase proportionally to the medium density. In the more realistic case of a dynamically expanding medium, the gluon radiation becomes anisotropic due to the presence of a preferred direction in the transverse plane with respect to the axis of propagation. This anisotropy translates into deformed jet-shapes which provide new posibilities to study these flows by high-pt measurements. 
Carlos A. Salgado