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Measurement of dijet cross sections for events with a leading neutron in photoproduction at HERA

Nuclear Physics B 596:1-2 (2001) 3-29

Authors:

J Breitweg, S Chekanov, M Derrick, D Krakauer, S Magill, B Musgrave, A Pellegrino, J Repond, R Stanek, R Yoshida, MCK Mattingly, P Antonioli, G Bari, M Basile, L Bellagamba, D Boscherini, A Bruni, G Bruni, G Cara Romeo, L Cifarelli, F Cindolo, A Contin, M Corradi, S de Pasquale, P Giusti, G Iacobucci, G Levi, A Margotti, T Massam, R Nania, F Palmonari, A Pesci, G Sartorelli, A Zichichi, C Amelung, A Bornheim, I Brock, K Coböken, J Crittenden, R Deffner, H Hartmann, K Heinloth, E Hilger, P Irrgang, HP Jakob, A Kappes, UF Katz, R Kerger, E Paul, J Rautenberg, H Schnurbusch, A Stifutkin, J Tandler, KC Voss, A Weber, H Wieber, DS Bailey, O Barret, NH Brook, B Foster, GP Heath, HF Heath, E Rodrigues, J Scott, RJ Tapper, M Capua, A Mastroberardino, M Schioppa, G Susinno, HY Jeoung, JY Kim, JH Lee, IT Lim, KJ Ma, MY Pac, A Caldwell, W Liu, X Liu, B Mellado, S Paganis, S Sampson, WB Schmidke, F Sciulli, J Chwastowski, A Eskreys, J Figiel, K Klimek, K Olkiewicz, K Piotrzkowski, MB Przybycień, P Stopa, L Zawiejski, B Bednarek, K Jeleń, D Kisielewska, AM Kowal, T Kowalski, E Rulikowska-Zarebska, L Suszycki, D Szuba

Abstract:

Differential cross sections for dijet photoproduction in association with a leading neutron using the reaction e+ + p → e+ + n + jet + jet + Xr have been measured with the ZEUS detector at HERA using an integrated luminosity of 6.4 pb-1. The fraction of dijet events with a leading neutron in the final state was studied as a function of the jet kinematic variables. The cross sections were measured for jet transverse energies Ejet T > 6 GeV, neutron energy En > 400 GeV, and neutron production angle θn < 0.8 mrad. The data are broadly consistent with factorization of the lepton and hadron vertices and with a simple one-pion-exchange model. © 2001 Elsevier Science B.V. All rights reserved.

Low-χ physics

Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 359:1779 (2001) 325-377

Abstract:

Low-χ physics is reviewed, with particular emphasis on searches for deviations from Gribov-Lipatov-Altarelli-Parisi (GLAP) evolution of the parton densities. Although there are several intriguing indications, both in HERA and in Tevatron data, as yet there is no unambiguous evidence for other than standard next-to-leading-order GLAP evolution. The framework of dipole models and saturation of parton densities is examined and confronted with the data. Although such models give a good qualitative description of the data, so do other, more conventional, explanations.

Measurement of open beauty production in photoproduction at HERA

European Physical Journal C 18:4 (2001) 625-637

Authors:

J Breitweg, S Chekanov, M Derrick, D Krakauer, S Magill, B Musgrave, A Pellegrino, J Repond, R Stanek, R Yoshida, MCK Mattingly, P Antonioli, G Bari, M Basile, L Bellagamba, D Boscherini, A Bruni, G Bruni, G Cara Romeo, L Cifarelli, F Cindolo, A Contin, M Corradi, S de Pasquale, P Giusti, G Iacobucci, G Levi, A Margotti, T Massam, R Nania, F Palmonari, A Pesci, G Sartorelli, A Zichichi, G Aghuzumtsyan, C Amelung, I Brock, K Coböken, S Goers, H Hartmann, K Heinloth, E Hilger, P Irrgang, HP Jakob, A Kappes, UF Katz, R Kerger, O Kind, E Paul, J Rautenberg, H Schnurbusch, A Stifutkin, J Tandler, KC Voss, A Weber, H Wieber, DS Bailey, O Barret, NH Brook, JE Cole, B Foster, GP Heath, HF Heath, S Robins, E Rodrigues, J Scott, RJ Tapper, M Capua, A Mastroberardino, M Schioppa, G Susinno, HY Jeoung, JY Kim, JH Lee, IT Lim, KJ Ma, MY Pac, A Caldwell, W Liu, X Liu, B Mellado, S Paganis, S Sampson, WB Schmidke, F Sciulli, J Chwastowski, A Eskreys, J Figiel, K Klimek, K Olkiewicz, K Piotrzkowski, MB Przybycień, P Stopa, L Zawiejski, B Bednarek, K Jeleń, D Kisielewska, AM Kowal, T Kowalski, E Rulikowska-Zarebska

Abstract:

The production and semi-leptonic decay of heavy quarks have been studied in the photoproduction process e+p → e+ + dijet + e- + X with the ZEUS detector at HERA using an integrated luminosity of 38.5 pb-1. Events with photon-proton centre-of-mass energies, Wγ±è, between 134 and 269 GeV and a photon virtuality, Q2, less than 1 GeV2 were selected requiring at least two jets of transverse energy Ejet1(2) T > 7(6) GeV and an electron in the final state. The electrons were identified by employing the ionisation energy loss measurement. The contribution of beauty quarks was determined using the transverse momentum of the electron relative to the axis of the closest jet, prel T. The data, after background subtraction, were fit with a Monte Carlo simulation including beauty and charm decays. The measured beauty cross section was extrapolated to the parton level with the b quark restricted to the region of transverse momentum pb T > = 5 GeV and pseudorapidity |ηb| < 2. The extrapolated cross section is 1.6 ± 0.4 (stat.)+0.3 -0.5(syst.)+0.2 -0.4(ext.) nb. The result is compared to a perturbative QCD calculation performed to next-to-leading order.

Low-x physics

PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES 359:1779 (2001) 325-377

Measurement of CP-violating asymmetries in B0 decays to CP eigenstates

PHYSICAL REVIEW LETTERS 86:12 (2001) 2515-2522

Authors:

B Aubert, D Boutigny, I De Bonis, JM Gaillard, K Jeremie, Y Karyotakis, JP Lees, P Robbe, V Tisserand, A Palano, GP Chen, JC Chen, ND Qi, G Rong, P Wang, YS Zhu, G Eigen, PL Reinertsen, B Stugu, B Abbott, GS Abrams, AW Borgland, AB Breon, DN Brown, J Button-Shafer, RN Cahn, AR Clark, S Dardin, C Day, SF Dow, T Elioff, Q Fan, I Gaponenko, MS Gill, FR Goozen, SJ Gowdy, A Gritsan, Y Groysman, RG Jacobsen, RC Jared, RW Kadel, J Kadyk, A Karcher, LT Kerth, I Kipnis, S Kluth, YG Kolomensky, JE Kral, R Lafever, C LeClerc, ME Levi, SA Lewis, C Lionberger, T Liu, M Long, G Lynch, M Marino, K Marks, AB Meyer, A Mokhtarani, M Momayezi, M Nyman, PJ Oddone, J Ohnemus, D Oshatz, S Patton, A Perazzo, C Peters, W Pope, M Pripstein, DR Quarrie, JE Rasson, NA Roe, A Romosan, MT Ronan, VG Shelkov, R Stone, AV Telnov, H von der Lippe, T Weber, WA Wenzel, MS Zisman, PG Bright-Thomas, TJ Harrison, CM Hawkes, A Kirk, DJ Knowles, SW O'Neale, AT Watson, NK Watson, T Deppermann, H Koch, J Krug, M Kunze, B Lewandowski, K Peters, H Schmuecker, M Steinke, JC Andress, NR Barlow, W Bhimji, N Chevalier, PJ Clark, WN Cottingham, N De Groot, N Dyce, B Foster, A Mass, JD McFall, D Wallom, FF Wilson, K Abe, C Hearty, TS Mattison, JA McKenna, D Thiessen, B Camanzi, S Jolly, AK McKemey, J Tinslay, VE Blinov, AD Bukin, DA Bukin, AR Buzykaev, MS Dubrovin, VB Golubev, VN Ivanchenko, GM Kolachev, AA Korol, EA Kravchenko, AP Onuchin, AA Salnikov, SI Serednyakov, YI Skovpen, VI Telnov, AN Yushkov, AJ Lankford, M Mandelkern, S McMahon, DP Stoker, A Ahsan, C Buchanan, S Chun, DB MacFarlane, S Prell, S Rahatlou, G Raven, V Sharma, S Burke, C Campagnari, B Dahmes, D Hale, PA Hart, N Kuznetsova, S Kyre, SL Levy, O Long, A Lu, JD Richman, W Verkerke, M Witherell, S Yellins, J Beringer, DE Dorfan, AM Eisner, A Frey, AA Grillo, M Grothe, CA Heusch, RP Johnson, W Kroeger, WS Lockman, T Puiliam, H Sadrozinski, T Schalk, RE Schmitz, BA Schumm, A Seiden, EN Spencer, M Turri, W Walkowiak, DC Williams, E Chen, GP Dubois-Felsmann, A Dvoretskii, JE Hanson, DG Hitlin, S Metzler, J Oyang, FC Porter, A Ryd, A Samuel, M Weaver, S Yang, RY Zhu, S Devmal, TL Geld, S Jayatilleke, SM Jayatilleke, G Mancinelli, BT Meadows, MD Sokoloff, P Bloom, S Fahey, WT Ford, F Gaede, WC van Hoek, DR Johnson, AK Michael, U Nauenberg, A Olivas, H Park, P Rankin, J Roy, S Sen, JG Smith, DL Wagner, J Blouw, JL Harton, M Krishnamurthy, A Soffer, WH Toki, DW Warner, RJ Wilson, J Zhang, T Brandt, J Brose, T Colberg, G Dahlinger, M Dickopp, RS Dubitzky, P Eckstein, H Futterschneider, R Krause, E Maly, R Müller-Pfefferkorn, S Otto, KR Schubert, R Schwierz, B Spaan, L Wilden, L Behr, D Bernard, GR Bonneaud, F Brochard, J Cohen-Tanugi, S Ferrag, G Fouque, F Gastaldi, P Matricon, PM de Freitas, C Renard, E Roussot, ST Jampens, C Thiebaux, G Vasileiadis, M Verderi, A Anjomshoaa, R Bernet, F Di Lodovico, A Khan, F Muheim, S Playfer, JE Swain, M Falbo, C Bozzi, S Dittongo, M Folegani, L Piemontese, E Treadwell, F Anulli, R Baldini-Ferroli, A Calcaterra, R de Sangro, D Falciai, G Finocchiaro, P Patteri, IM Peruzzi, M Piccolo, Y Xie, A Zallo, S Bagnasco, A Buzzo, R Contri, G Crosetti, M Lo Vetere, M Macri, MR Monge, M Pallavicini, S Passaggio, FC Pastore, C Patrignani, MG Pia, E Robutti, A Santroni, M Morii, R Bartoldus, T Dignan, R Hamilton, U Mallik, J Cochran, HB Crawley, PA Fischer, J Lamsa, R McKay, WT Meyer, EI Rosenberg, JN Albert, C Beigbeder, M Benkebil, D Breton, R Cizeron, S Du, G Grosdidier, C Hast, A Höcker, V LePeltier, AM Lutz, S Plaszczynski, MH Schune, S Trincaz-Duvoid, K Truong, A Valassi, G Wormser, RM Bionta, V Brigijevic, A Brooks, O Fackler, D Fujino, DJ Lange, M Mugge, TG O'Connor, B Pedrotti, X Shi, K van Bibber, TJ Wenaus, DM Wright, CR Wuest, B Yamamoto, M Carroll, JR Fry, E Gabathuler, R Gamet, M George, M Kay, DJ Payne, RJ Sloane, C Touramanis, ML Aspinwall, DA Bowerman, PD Dauncey, U Egede, I Eschrich, NJW Gunawardane, R Martin, JA Nash, DR Price, P Sanders, D Smith, DE Azzopardi, JJ Back, P Dixon, PF Harrison, D Newman-Coburn, RJL Potter, HW Shorthouse, P Strother, PB Vidal, MI Williams, G Cowan, S George, MG Green, A Kurup, CE Marker, P McGrath, TR McMahon, F Salvatore, I Scott, G Vaitsas, D Brown, CL Davis, K Ford, Y Li, J Pavlovich, J Allison, RJ Barlow, JT Boyd, J Fullwood, F Jackson, GD Laffery, N Savvas, ET Simopoulos, RJ Thompson, JH Weatherall, R Bard, A Farbin, A Jawahery, V Lillard, J Olsen, DA Roberts, JR Schieck, G Blaylock, C Dallapiccola, KT Flood, SS Hertzbach, R Kofler, CS Lin, H Staengle, S Willocq, J Wittlin, B Brau, R Cowan, G Sciolla, F Taylor, RK Yamamoto, DI Britton, M Milek, PM Patel, J Trischuk, F Lanni, F Palombo, JM Bauer, M Booke, L Cremaldi, V Eschenberg, R Kroeger, M Reep, J Reidy, DA Sanders, DJ Summers, M Beaulieu, JP Martin, JY Nief, R Seitz, P Taras, V Zacek, H Nicholson, CS Sutton, N Cavallo, C Cartaro, G De Nardo, F Fabozzi, C Gatto, L Lista, P Paolucci, D Piccolo, C Sciacca, JM LoSecco, JRG Alsmiller, TA Gabriel, T Handler, J Heck, JE Brau, P Frey, M Iwasaki, NB Sinev, D Strom, E Borsato, F Colecchia, F Dal Corso, F Galeazzi, M Maroni, M Marzolla, G Michelon, M Morandin, M Posocco, M Rotondo, F Simonetto, R Stroili, E Torassa, C Voci, P Bailly, M Benayoun, H Briand, J Chauveau, P David, C De la Vaissière, L Del Buono, JF Genat, O Hamon, F Le Diberder, H Lebbolo, P Leruste, J Lory, L Martin, L Roos, J Stark, S Versillé, B Zhang, PF Manfredi, L Ratti, V Re, V Speziali, ED Frank, L Gladney, QH Guo, JH Panetta, C Angelini, G Batignani, S Bettarini, M Bondioli, F Bosi, M Carpinelli, F Forti, MA Giorgi, A Lusiani, F Martinez-Vidal, M Morganti, N Neri, E Paoloni, M Rama, G Rizzo, F Sandrelli, G Simi, G Triggiani, J Walsh, M Haire, D Judd, K Paick, L Turnbull, DE Wagoner, J Albert, C Bula, R Fernholz, C Lu, KT McDonald, V Miftakov, B Sands, SF Schaffner, AJS Smith, A Tumanov, EW Varnes, F Bronzini, A Buccheri, C Bulfon, G Cavoto, D del Re, R Faccini, F Ferrarotto, F Ferroni, K Fratini, E Lamanna, E Leonardi, MA Mazzoni, S Morganti, G Piredda, ES Tehrani, M Serra, C Voena, R Waldi, PE Jacques, M Kalelkar, RJ Plano, T Adye, B Claxton, B Franek, S Galagedera, NI Geddes, GP Gopa, J Lidbury, SM Xella, R Aleksan, P Besson, P Bourgeois, G De Domenico, S Emery, A Gaidot, SF Ganzhur, L Gosset, GH de Monchenault, W Kozanecki, M Langer, GW London, B Mayer, B Serfass, G Vasseur, C Yeche, M Zito, N Copty, MV Purohit, H Singh, FX Yumiceva, I Adam, PL Anthony, D Aston, K Baird, J Bartelt, J Becla, R Bell, E Bloom, CT Boeheim, AM Boyarski, RF Boyce, F Bulos, W Burgess, B Byers, G Calderini, R Claus, MR Convery, R Coombes, L Cottrell, DP Coupal, DH Coward, WW Craddock, H DeSstaebler, J Dorfan, M Doser, W Dunwoodie, S Ecklund, TH Fieguth, RC Field, DR Freytag, T Glanzman, GL Godfrey, P Grosso, G Haller, A Hanushevsky, J Harris, A Hasan, JL Hewett, T Himel, ME Huffer, WR Innes, CP Jessop, H Kawahara, L Keller, MH Kelsey, P Kim, LA Klaisner, ML Kocian, HJ Krebs, PF Kunz, U Langenegger, W Langeveld, DWGS Leith, SK Louie, S Luitz, V Luth, HL Lynch, J MacDonald, G Manzin, H Marsiske, M McCulloch, D McShurley, S Menke, R Messner, S Metcalfe, KC Moffeit, R Mount, DR Muller, D Nelson, M Nordby, CP O'Grady, FG O'Neill, G Oxoby, T Pavel, J Perl, S Petrak, G Putallaz, H Quinn, PE Raines, BN Ratcliff, R Reif, SH Robertson, LS Rochester, A Roodman, JJ Russell, L Sapozhnikov, OH Saxton, T Schietinger, RH Schindler, J Schwiening, JT Seeman, VV Serbo, K Skarpass, A Snyder, A Soha, SM Spanier, A Stah, J Stelzer, D Su, MK Sullivan, M Talby, HA Tanaka, J Va'vra, SR Wagner, AJR Weinstein, JL White, U Wienands, WJ Wisniewski, CC Young, G Zioulas, PR Burchat, CH Cheng, D Kirkby, TI Meyer, C Roat, A De Silva, R Henderson, S Berridge, W Bugg, H Cohn, E Hart, AW Weidemann, T Benninger, JM Izen, I Kitayama, XC Lou, M Turcotte, F Bianchi, M Bona, B Di Girolamo, D Gamba, A Smol, D Zanin, L Bosisio, G Della Ricca, L Lanceri, A Pompili, P Poropat, G Vuagnin, RS Panvini, CM Brown, R Kowalewski, JM Roney, HR Band, E Charles, S Dasu, P Elmer, H Hu, JR Johnson, J Nielsen, W Orejudos, Y Pan, R Prepost, IJ Scott, JH von Wimmersperg-Toeller, SL Wu, Z Yu, H Zobernig, TMB Kordich, TB Moore, H Neal