Quark-Antiquark Production in DIS Diffractive Dissociation

We calculate the cross section for the production of two jets with large transverse momenta k in DIS diffractive dissociation for both transverse and longitudinally polarized photons. The scale which defines the hardness of the Pomeron is found to be k Q 2 +M M . We present analytic expressions and discuss numerical results relevant for the diffractive dissociation at HERA. 1.) The diffractive dissociation of the photon in deep inelastic ep-scattering at HERA has recently attracted much interest. As for the inclusive diffractive cross section attention has been given to the question whether the Pomeron which describes the energy dependence of this process is closer to the soft Pomeron which describes the high energy behavior of hadron-hadron scattering or whether it resembles the hard Pomeron observed in the proton structure function at small x. Whereas earlier analysis [1, 2] of HERA data seem to favor the first alternative, a recent analysis [3] presents evidence for a strong admixture of the hard Pomeron. A natural way to gain further clarification is a more detailed analysis of the diffractive final state. Electroproduction of vector mesons and photoproduction of J/Ψ have been analysed [4] and compared [5] with both the soft and the hard Pomeron, and they seem to favor a harder Pomeron. A new class of final states which allow to enhance the hard Pomeron component are jets with large transverse momenta [6, 7, 8]. The simplest configuration are two-jet events with the jets originating from qq̄ pairs; for larger invariant masses M one expects events with additional production of gluon jets to become dominant. Supported by Bundesministerium für Forschung und Technologie, Bonn, Germany under Contract 05 6HH93P(5) and EEC Program ”Human Capital and Mobility” through Network ”Physics at High Energy Colliders” under Contract CHRX-CT93-0357 (DG12 COMA). Supported by the U.S. Department of Energy, Division of High Energy Physics, Contract W-31-109-ENG-38.