Observation of isolated high-ET photons in photoproduction at HERA
Physics Letters B Elsevier 413:1-2 (1997) 201-216
Authors:
ZEUS Collaboration, J Breitweg, M Derrick, D Krakauer, S Magill, D Mikunas, B Musgrave, J Repond, R Stanek, RL Talaga, R Yoshida, H Zhang, MCK Mattingly, F Anselmo, P Antonioli, G Bari, M Basile, L Bellagamba, D Boscherini, A Bruni, G Bruni, G Cara Romeo, G Castellini, L Cifarelli, F Cindolo, A Contin, M Corradi, S De Pasquale, I Gialas, P Giusti, G Iacobucci, G Laurenti, G Levi, A Margotti, T Massam, R Nania, F Palmonari, A Pesci, A Polini, F Ricci, G Sartorelli, Y Zamora Garcia, A Zichichi, C Amelung, A Bornheim, I Brock, K Coböken, J Crittenden, R Deffner, M Eckert, M Grothe, H Hartmann, K Heinloth, L Heinz, E Hilger, H-P Jakob, UF Katz, R Kerger, E Paul, M Pfeiffer, Ch Rembser, J Stamm, R Wedemeyer, H Wieber, DS Bailey, S Campbell-Robson, WN Cottingham, B Foster, R Hall-Wilton, ME Hayes, GP Heath, HF Heath, D Piccioni, DG Roff, RJ Tapper, M Arneodo, R Ayad, M Capua, A Garfagnini, L Iannotti, M Schioppa, G Susinno, JY Kim, JH Lee, IT Lim, MY Pac, A Caldwell, N Cartiglia, Z Jing, W Liu, B Mellado, JA Parsons, S Ritz, S Sampson, F Sciulli, PB Straub, Q Zhu, P Borzemski, J Chwastowski, A Eskreys, Z Jakubowski, MB Przybycień, M Zachara, L Zawiejski, L Adamczyk, B Bednarek, M Bukowy, K Jeleń, D Kisielewska, T Kowalski, M Przybycień, E Rulikowska-Zarȩbska, L Suszycki, J Zaja̧c, Z Duliński, A Kotański, G Abbiendi, LAT Bauerdick, U Behrens, H Beier, JK Bienlein, G Cases, O Deppe, K Desler, G Drews, U Fricke, DJ Gilkinson, C Glasman, P Göttlicher, J Große-Knetter, T Haas, W Hain, D Hasell, KF Johnson, M Kasemann, W Koch, U Kötz, H Kowalski, J Labs, L Lindemann, B Löhr, M Löwe, O Mańczak, J Milewski, T Monteiro, JST Ng, D Notz, K Ohrenberg, IH Park, A Pellegrino, F Pelucchi, K Piotrzkowski, M Roco, M Rohde, J Roldán, JJ Ryan, AA Savin, U Schneekloth, F Selonke, B Surrow, E Tassi, T Voß, D Westphal, G Wolf, U Wollmer, C Youngman, AF Żarnecki, W Zeuner, BD Burow, HJ Grabosch, A Meyer, S Schlenstedt, G Barbagli, E Gallo, P Pelfer, G Maccarrone, L Votano, A Bamberger, S Eisenhardt, P Markun, T Trefzger, S Wölfle, JT Bromley, NH Brook, PJ Bussey, AT Doyle, DH Saxon, LE Sinclair, E Strickland, ML Utley, R Waugh, AS Wilson, I Bohnet, N Gendner, U Holm, A Meyer-Larsen, H Salehi, K Wick, LK Gladilin, D Horstmann, D Kçira, R Klanner, E Lohrmann, G Poelz, W Schott, F Zetsche, TC Bacon, I Butterworth, JE Cole, VL Harris, G Howell, BHY Hung, L Lamberti, KR Long, DB Miller, N Pavel, A Prinias, JK Sedgbeer, D Sideris, AF Whitfield, U Mallik, SM Wang, JT Wu, P Cloth, D Filges, JI Fleck, T Ishii, M Kuze, M Nakao, K Tokushuku, S Yamada, Y Yamazaki, SH An, SB Lee, SW Nam, HS Park, SK Park, F Barreiro, JP Fernández, G García, R Graciami, JM Hernández, L Hervás, L Labarga, M Martínez, J del Peso, J Puga, J Terrón, JF de Trocóniz, F Corriveau, DS Hanna, J Hartmann, LW Hung, JN Lim, WN Murray, A Ochs, M Riveline, DG Stairs, M St-Laurent, R Ullmann, T Tsurugai, V Bashkirov, BA Dolgoshein, A Stifutkin, GL Bashindzhagyan, PF Ermolov, Yu A Golubkov, LA Khein, NA Korotkova, IA Korzhavina, VA Kuzmin, O Yu Lukina, AS Proskuryakov, LM Shcheglova, AN Solomin, SA Zotkin, C Bokel, M Botje, N Brümmer, F Chlebana, J Engelen, P Kooijman, A van Sighem, H Tiecke, N Tuning, W Verkerke, J Vossebeld, M Vreeswijk, L Wiggers, E de Wolf, D Acosta, B Bylsma, LS Durkin, J Gilmore, CM Ginsburg, CL Kim, TY Ling, P Nylander, TA Romanowski, HE Blaikley, RJ Cashmore, AM Cooper-Sarkar, RCE Devenish, JK Edmonds, N Harnew, M Lancaster, JD McFall, C Nath, VA Noyes, A Quadt, O Ruske, JR Tickner, H Uijterwaal, R Walczak, DS Waters, A Bertolin, R Brugnera, R Carlin, F Dal Corso, U Dosselli, S Limentani, M Morandin, M Posocco, L Stanco, R Stroili, C Voci, J Bulmahn, RG Feild, BY Oh, JR Okrasiński, JJ Whitmore, Y Iga, G D'Agostini, G Marini, A Nigro, M Raso, JC Hart, NA McCubbin, TP Shah, D Epperson, C Heusch, JT Rahn, HF-W Sadrozinski, A Seiden, DC Williams, O Schwarzer, AH Walenta, H Abramowicz, G Briskin, S Dagan, S Kananov, A Levy, T Abe, T Fusayasu, M Inuzuka, K Nagano, I Suzuki, K Umemori, T Yamashita, R Hamatsu, T Hirose, K Homma, S Kitamura, T Matsushita, K Yamauchi, R Cirio, M Costa, MI Ferrero, S Maselli, V Monaco, C Peroni, MC Petrucci, R Sacchi, A Solano, A Staiano, M Dardo, DC Bailey, M Brkic, C-P Fagerstroem, GF Hartner, KK Joo, GM Levman, JF Martin, RS Orr, S Polenz, CR Sampson, D Simmons, RJ Teuscher, JM Butterworth, CD Catterall, TW Jones, PB Kaziewicz, JB Lane, RL Saunders, J Shulman, MR Sutton, B Lu, LW Mo, J Ciborowski, G Grzelak, M Kasprzak, K Muchorowski, RJ Nowak, JM Pawlak, R Pawlak, T Tymieniecka, AK Wróblewski, JA Zakrzewski, M Adamus, C Coldewey, Y Eisenberg, D Hochman, U Karshon, D Revel, WF Badgett, D Chapin, R Cross, S Dasu, C Foudas, RJ Loveless, S Mattingly, DD Reeder, WH Smith, A Vaiciulis, M Wodarczyk, S Bhadra, WR Frisken, M Khakzad, WB Schmidke
Abstract:
Events containing an isolated prompt photon with high transverse energy, together with a balancing jet, have been observed for the first time in photoproduction at HERA. The data were taken with the ZEUS detector, in a γp centre of mass energy range 120–250 GeV. The fraction of the incoming photon energy participating in the production of the prompt photon and the jet, xγ, shows a strong peak near unity, consistent with LO QCD Monte Carlo predictions. In the transverse energy and pseudorapidity range 5 ≤ ETγ < 10 GeV, −0.7 ≤ ηγ < 0.8, ETjet ≥ 5 GeV, and −1.5 ≤ ηjet ≤ 1.8, with xγOBS > 0.8, the measured cross section is 15.3 ± 3.8 ± 1.8 pb, in good agreement with a recent NLO calculation.
