ENERGY AND COLOR-FLOW IN DIJET RAPIDITY GAPS

When rapidity gaps in high-p, dijet events are identified by energy fl ow in the central region, they may be calculated from factorized cross sections in perturbative QCD, up to corrections that behave as invers e powers of the central region energy. Although power-suppressed corre ctions may be important, a perturbative calculation of dijet rapidity gaps in p (p) over bar scattering, using a valence quark approximation , reproduces the overall features observed at the Fermilab Tevatron. i n this formulation, the average color content of the hard scattering i s well defined. We find that hard dijet rapidity gaps in quark-antiqua rk scattering are not due to singlet exchange alone. [S0031-9007(98)07 371-2].