Diffractive dijet photoproduction in ep collisions at HERA
H1 Collaboration (ukupan broj autora: 221)
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Measurements are presented of single and double-differential dijet cross sections in diffractive photoproduction based on a data sample with an integrated luminosity of 47 pb(-1). The events are of the type ep - GT eXY, where the hadronic system X contains at least two jets and is separated by a large rapidity gap from the system Y, which consists of a leading proton or low-mass proton excitation. The dijet cross sections are compared with QCD calculations at next-to-leading order and with a Monte Carlo model based on leading order matrix elements with parton showers. The measured cross sections are smaller than those obtained from the next-to-leading order calculations by a factor of about 0.6. This suppression factor has no significant dependence on the fraction x (gamma) of the photon four-momentum entering the hard subprocess. Ratios of the diffractive to the inclusive dijet cross sections are measured for the first time and are compared with Monte Carlo models.
Source:European Physical Journal C. Particles and Fields, 2010, 70, 1-2, 15-37
- Helmholtz Association (HGF) [VH-NG-401], Bundesministerium fur Bildung und Forschung, FRG [05H09GUF, 05H09VHC, 05H09VHF, 05H16PEA], UK Science and Technology Facilities Council, UK Particle Physics and Astronomy Research Council, FNRS-FWO-Vlaanderen, IISN-IIKW, IWT, Interuniversity Attraction Poles Programme, Belgian Science Policy, Polish Ministry of Science and Higher Education [DPN/N168/DESY/2009], Deutsche Forschungsgemeinschaft, VEGA SR [2/7062/27], Swedish Natural Science Research Council, Ministry of Education of the Czech Republic [LC527, INGO-1P05LA259, MSM0021620859], Swiss National Science Foundation, CONACYT, Mexico [48778-F], Russian Foundation for Basic Research (RFBR) [1329.2008.2], European Social Fund, (EPEAEK II)-PYTHAGORAS II, Romanian National Authority for Scientific Research [PN 09370101]