Double Pomeron Jet Cross Sections

We treat hadron-hadron collisions where the final state is kinematically of the kind associated with double-pomeron-exchange (DPE) and has large transverse momentum jets. We show that in addition to the conventional factorized (FDPE) contribution, there is a non-factorized (NDPE) contribution which has no pomeron beam jet. Within a simple model we compute DPE-two-jet total and differential cross sections at Tevatron energy scales, and show that the NDPE contribution is dominant. When two hadrons collide at high energy, there is about a 10% chance that one of the incoming hadrons will survive into the final state, while losing only a small fraction of its energy. Such events are called diffractive. The object that is exchanged in diffractive processes is called the “pomeron”. A primary characteristic is that cross sections with pomeron exchange are approximately independent of energy at high energy; the pomeron has spin close to unity [1]. Moreover, there has been growing experimental evidence that within diffractive events, hard QCD processes can also occur, i.e., processes with a large momentum transfer. Such “diffractive hard scattering” has been been seen not only in hadron-hadron scattering by the UA1 and UA8 experiments [2,3], but also in electronproton scattering at the H1 [4] and ZEUS [5] experiments, both in the deep-inelastic regime and in photoproduction. An interesting class of diffractive hadron-hadron collisions, is where both hadrons survive unscathed, but leave a remnant system in the central region of final-state rapidity. Such events are called double-pomeron exchange (DPE) events [6,7]. In effect, one can try to consider such processes as pomeron-pomeron collisions. Our purpose in this paper is to explore the properties of jet production in DPE events, and in particular the breakdown of hard-scattering factorization. Jet production by DPE has been reported [8] in the UA1 detector. The simplest model for diffractive hard scattering is due to Ingelman and Schlein [9]. They treat each exchanged pomeron as a particle, in the same manner as one obtains phoE-mail: [email protected] E-mail: [email protected]