PHENIX Hard Scattering PWG

The Main Physics Unknown

Hard processes have the benefit that they can be predicted by perturbative QCD. There are some complications like higher order effects, intrinsic and multiple scattering induced initial state $k_T$, structure functions in nuclei. However the main physics unknown is the exact prediction of of the energy loss in hot/dense matter in the limit at which we work, i.e. finite energy, finite length. Thus we shall be in the fortunate position of being able to interpret our measurements by quantifying them as a function of `centrality' in Au+Au collisions or by comparison to p-p measurements without the oppression of a `standard model' which `must be obeyed.'
Michael J. Tannenbaum 7/28/99 - contact: mjt@bnl.gov