Energy and Color Flow in Dijet Rapidity Gaps

When rapidity gaps in high- p_T dijet events are identified by energy flow in the central region, they may be calculated from factorized cross sections in perturbative QCD, up to corrections that behave as inverse powers of the central region energy. Although power-suppressed corrections may be important, a perturbative calculation of dijet rapidity gaps in pp̅ scattering, using a valence quark approximation, reproduces the overall features observed at the Fermilab Tevatron. In this formulation, the average color content of the hard scattering is well defined. We find that hard dijet rapidity gaps in quark-antiquark scattering are not due to singlet exchange alone.