SPLITTING THE POMERON INTO 2 JETS - A NOVEL PROCESS AT HERA

We study a novel property of large rapidity-gap events in deep inelastic scattering at HERA: splitting the pomeron into two jets in the photon-pomeron fusion reaction gamma*IP --> qqBAR. It gives rise to the diffraction dissociation of virtual photons into the back-to-back jets. We find that at large invariant mass M of two jets, M2 >> Q2, the transverse momentum of jets comes from the intrinsic transverse momentum of gluons in the pomeron, and the photon-pomeron fusion direcly probes the diffrential gluon structure function of the proton partial derivative G(x, q2)/partial derivative log q2 at the virtuality q2 is similar to k2. We present estimates for the jet production cross section, which show the process is easily measurable at HERA.