Hard-scattering and Jets from RHIC to LHC: a critical review

Abstract

Jets in hadron collisions are very complicated with a long learning curve replete with errors. In relativistic heavy ion (RHI) collisions, it is likely that jets will be much more complicated with an even longer and more difficult learning curve. Hard scattering is more easily observed via single particle and few particle correlation measurements. The main advantage of jets is higher rate at large $p_T$, plus the possibility of detailed studies of soft fragmentation if the soft fragments can be separated from the background. A critical review of the possibility of using jets as a probe of hard-scattering in RHI collisions is presented along with other probes and measurements which the author considers much more likely to reveal the interesting physics in Pb+Pb collisions at the LHC. Finally, a list of unanswered questions raised by results at RHIC is presented.