Gluon Radiation Patterns in Pomeron Exchange Events
  Color singlet two gluon exchange provides a perturbative model for the pomeron. This mechanism is thought to explain the production of rapidity gaps in hard dijet events at the Tevatron. It is shown that in $qQ$ scattering via two gluon color singlet exchange the emission of soft gluons follows closely the pattern found for $t$-channel photon exchange. Gluon emission is strongly suppressed between the two quark jets. After hadronization this leads to a depressed level of hadronic activity between the jets and thus allows the formation of rapidity gaps. 
D. Zeppenfeld