  Two-particle azimuthal correlations in central Au+Au collisional at RHIC have
revealed a broadened away-side structure, with respect to perpherial Au+Au, pp,
and d+Au. This could be explained by different physics mechanisms such as:
large angle gluon radiation, deflected jets, Cerenkov gluon radiation, and
conical flow generated by hydrodynamic shock-waves. We can discriminate the
scenarios with conical emission, Cerenkov radiation and conical flow, from the
other mechanisms though three-particle correlations. In addition, the
associated particle pT dependence can be used to distinguish conical flow from
simple Cerenkov gluon radiation. We will discuss three-particle correlation
analyses that have been performed at RHIC and what can be done at the LHC.
