Eur. Phys. J. C 24, 517-527 (2002)
Energy flow and rapidity gaps between jets in photoproduction at HERAThe H1 Collaboration
(Received: 8 March 2002 / Published online: 5 July 2002)
Dijet events in photon-proton collisions in which there is a large pseudorapidity separation between the two highest ET jets are studied with the H1 detector at HERA. The inclusive dijet cross sections are measured as functions of the longitudinal momentum fractions of the proton and photon which participate in the production of the jets, xpjets and respectively, , the pseudorapidity separation between the two highest ET jets, and ETgap, the total summed transverse energy between the jets. Rapidity gap events are defined as events in which ETgap is less than ETcut, for ETcut varied between 0.5 and 2.0 GeV. The fraction of dijet events with a rapidity gap is measured differentially in , xpjets and . An excess of events with rapidity gaps at low values of ETcut is observed above the expectation from standard photoproduction processes. This excess can be explained by the exchange of a strongly interacting colour singlet object between the jets.
© Società Italiana di Fisica, Springer-Verlag 2002