1. The Q(2) dependence of dijet cross sections in gamma p interactions at HERA
- Author
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Breitweg, J, Chekanov, S, Derrick, M, Krakauer, D, Magill, S, Musgrave, B, Pellegrino, A, Repond, J, Stanek, R, Yoshida, R, Mattingly, M C K, Abbiendi, G, Anselmo, F, Antonioli, P, Bari, G, Basile, M, Bellagamba, L, Boscherini, D, Bruni, A, Bruni, G, Romeo, G C, Castellini, G, Cifarelli, L, Cindolo, F, Contin, A, Coppola, N, Corradi, M, De Pasquale, S, Giusti, P, Iacobucci, G, Laurenti, G, Levi, G, Margotti, A, Massam, T, Nania, R, Palmonari, F, Pesci, A, Polini, A, Sartorelli, G, Garcia, Y Z, Zichichi, A, Amelung, C, Bornheim, A, Brock, I, Coboken, K, Crittenden, J, Deffner, R, Hartmann, H, Heinloth, K, Hilger, E, Irrgang, P, Jakob, H P, Kappes, A, Katz, U F, Kerger, R, Paul, E, Schnurbusch, H, Stifutkin, A, Tandler, J, Voss, K C, Weber, A, Wieber, H, Bailey, D S, Barret, O, Brook, N H, Foster, B, Heath, G P, Heath, H F, McFall, J D, Piccioni, D, Rodrigues, E, Scott, J, Tapper, R J, Capua, M, Mastroberardino, A, Schioppa, M, Susinno, G, Jeoung, H Y, Kim, J Y, Lee, J H, Lim, I T, Ma, K J, Pac, M Y, Caldwell, A, Liu, W, Liu, X, Mellado, B, Paganis, S, Sacchi, R, Sampson, S, Sciulli, F, Chwastowski, J, Eskreys, A, Figiel, J, Klimek, K, Olkiewicz, K, Piotrzkowski, K, Przybycien, M B, Stopa, P, Zawiejski, L, Adamczyk, L, Bednarek, B, Jelen, K, Kisielewska, D, Kowal, A M, Kowalski, T, Przybycien, M, Rulikowska-Zarebska, E, Suszycki, L, Szuba, D, Kotanski, A, Bauerdick, L A T, Behrens, U, Bienlein, J K, Burgard, C, Desler, K, Drews, G, Fox-Murphy, A, Fricke, U, Goebel, F, Gottlicher, P, Graciani, R, Haas, T, Hain, W, Hartner, G F, Hasell, D, Hebbel, K, Johnson, K F, Kasemann, M, Koch, W, Kotz, U, Kowalski, H, Lindemann, L, Lohr, B, Martinez, M, Milite, M, Monteiro, T, Moritz, M, Notz, D, Pelucchi, F, Petrucci, M C, Rohde, M, Saull, P R B, Savin, A A, Schneekloth, U, Selonke, F, Sievers, M, Stonjek, S, Tassi, E, Wolf, G, Wollmer, U, Youngman, C, Zeuner, W, Coldewey, C, Grabosch, H J, Viani, A L D, Meyer, A, Schlenstedt, S, Straub, P B, Barbagli, G, Gallo, E, Pelfer, P, Maccarrone, G, Votano, L, Bamberger, A, Benen, A, Eisenhardt, S, Markun, P, Raach, P, Wolfle, S, Bussey, P J, Doyle, A T, Lee, S W, Macdonald, N, McCance, G J, Saxon, D H, Sinclair, L E, Skillicorn, I O, Waugh, R, Bohnet, I, Gendner, N, Holm, U, Meyer-Larsen, A, Salehi, H, Wick, K, Dannheim, D, Garfagnini, A, Gialas, I, Gladilin, L K, Kcira, D, Klanner, R, Lohrmann, E, Poelz, G, Zetsche, F, Goncalo, R, Long, K R, Miller, D B, Tapper, A D, Walker, R, Mallik, U, Cloth, P, Filges, D, Ishii, T, Kuze, M, Nagano, K, Tokushuku, K, Yamada, S, Yamazaki, Y, Ahn, S H, An, S H, Hong, S J, Lee, S B, Nam, S W, Park, S K, Lim, H, Park, I H, Son, D, Barreiro, F, Garcia, G, Glasman, C, Gonzalez, O, Labarga, L, del Peso, J, Redondo, I, Terron, J, Barbi, M, Corriveau, F, Hanna, D S, Ochs, A, Padhi, S, Riveline, M, Stairs, D G, Wing, M, Tsurugai, T, Bashkirov, V, Dolgoshein, B A, Dementiev, R K, Ermolov, P F, Golubkov, Y A, Katkov, I I, Khein, L A, Korotkova, N A, Korzhavina, I A, Kuzmin, V A, Lukina, O Y, Proskuryakov, A S, Shcheglova, L M, Solomin, A N, Vlasov, N N, Zotkin, S A, Bokel, C, Botje, M, Brummer, N, Engelen, J, Grijpink, S, Koffeman, E, Kooijman, P, Schagen, S, van Sighem, A, Tiecke, H, Tuning, N, Velthuis, J J, Vossebeld, J, Wiggers, L, de Wolf, E, Bylsma, B, Durkin, L S, Gilmore, J, Ginsburg, C M, Kim, C L, Ling, T Y, Nylander, P, Boogert, S, Cooper-Sarkar, A M, Devenish, R C E, Grosse-Knetter, J, Matsushita, T, Ruske, O, Sutton, M R, Walczak, R, Bertolin, A, Brugnera, R, Carlin, R, Dal Corso, F, Dosselli, U, Dusini, S, Limentani, S, Morandin, M, Posocco, M, Stanco, L, Stroili, R, Voci, C, Iannotti, L, Oh, B Y, Okrasinski, J R, Toothacker, W S, Whitmore, J J, Iga, Y, D'Agostini, G, Marini, G, Nigro, A, Cormack, C, Hart, J C, McCubbin, N A, Shah, T P, Epperson, D, Heusch, C, Sadrozinski, H F W, Seiden, A, Wichmann, R, Williams, D C, Pavel, N, Abramowicz, H, Dagan, S, Kananov, S, Kreisel, A, Levy, A, Abe, T, Fusayasu, T, Umemori, K, Yamashita, T, Hamatsu, R, Hirose, T, Inuzuka, M, Kitamura, S, Nishimura, T, Arneodo, M, Cartiglia, N, Cirio, R, Costa, M, Ferrero, M I, Maselli, S, Monaco, V, Peroni, C, Ruspa, M, Solano, A, Staiano, A, Dardo, M, Bailey, D C, Fagerstroem, C P, Galea, R, Koop, T, Levman, G M, Martin, J F, Orr, R S, Polenz, S, Sabetfakhri, A, Simmons, D, Butterworth, J M, Catterall, C D, Hayes, M E, Heaphy, E A, Jones, T W, Lane, J B, West, B J, Ciborowski, J, Ciesielski, R, Grzelak, G, Nowak, R J, Pawlak, J M, Pawlak, R, Smalska, B, Tymieniecka, T, Wroblewski, A K, Zakrzewski, J A, Zarnecki, A F, Adamus, M, Gadaj, T, Deppe, O, Eisenberg, Y, Hochman, D, Karshon, U, Badgett, W F, Chapin, D, Cross, R, Foudas, C, Mattingly, S, Reeder, D D, Smith, W H, Vaiciulis, A, Wildschek, T, Wodarczyk, M, Deshpande, A, Dhawan, S, Hughes, V W, Bhadra, S, Cole, J E, Frisken, W R, Hall-Wilton, R, Khakzad, M, Menary, S, Schmidke, W B, ZEUS Collaborat, and Zeus (IHEF, IoP, FNWI)
- Subjects
Nuclear and High Energy Physics ,Particle physics ,Photon ,LEADING ORDER QCD ,Virtual particle ,FOS: Physical sciences ,ZEUS ,PHOTON STRUCTURE-FUNCTION ,STRUCTURE-FUNCTION F-2(GAMMA) ,VIRTUAL PHOTON ,JET PRODUCTION ,PARTON DISTRIBUTIONS ,HADRON-COLLISIONS ,HARD SCATTERING ,PHOTOPRODUCTION ,GEV2 ,Parton ,Elementary particle ,7. Clean energy ,01 natural sciences ,High Energy Physics - Experiment ,Nuclear physics ,High Energy Physics - Experiment (hep-ex) ,0103 physical sciences ,010306 general physics ,Nuclear Experiment ,QC ,Physics ,Research Groups and Centres\Physics\Low Temperature Physics ,010308 nuclear & particles physics ,Faculty of Science\Physics ,Perturbative QCD ,HERA ,Photon structure function ,Massless particle ,High Energy Physics::Experiment - Abstract
The dependence of the photon structure on the photon virtuality, Q^2, is studied by measuring the reaction e^+p\to e^+ + {\rm jet} + {\rm jet} + {\rm X} at photon-proton centre-of-mass energies 134 < W < 223 GeV. Events have been selected in the Q^2 ranges \approx 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_gamma. The ratio of the dijet cross section with x_gamma < 0.75 to that with x_gamma > 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., 15 pages and 4 figures
- Published
- 2000