The Q**2 dependence of dijet cross-sections in gamma p interactions at HERA
Collaboration
16 pages
Published in:
- Phys.Lett.B 479 (2000) 37-52
e-Print:
- hep-ex/0002010 [hep-ex]
Report number:
- DESY-00-017
Experiments:
Citations per year
Abstract: (Elsevier)
The dependence of the photon structure on the photon virtuality, Q 2 , is studied by measuring the reaction e + p → e + +jet+jet+X at photon-proton centre-of-mass energies 134< W <223 GeV. Events have been selected in the Q 2 ranges ≈ 0 GeV 2 , 0.1–0.55 GeV 2 , and 1.5–4.5 GeV 2 , having two jets with transverse energy E T jet >5.5 GeV in the final state. The dijet cross section has been measured as a function of the fractional momentum of the photon participating in the hard process, x γ OBS . The ratio of the dijet cross section with x γ OBS <0.75 to that with x γ OBS >0.75 decreases as Q 2 increases. The data are compared with the predictions of NLO pQCD and leading-order Monte Carlo programs using various parton distribution functions of the photon. The measurements can be interpreted in terms of a resolved photon component that falls with Q 2 but remains present at values of Q 2 up to 4.5 GeV 2 . However, none of the models considered gives a good description of the data.Note:
- 15 pages and 4 figures Report-no: DESY-00-017
- positron p: colliding beams
- exchange: one-photon
- jet: photoproduction
- final state: (2jet)
- channel cross section: momentum dependence
- momentum transfer dependence
- photon: structure function
- momentum spectrum: parton
- quantum chromodynamics: perturbation theory
- photon: resolved
References(63)
Figures(4)