Experimental discrimination between charge 2e/3 top quark and charge 4e/3 exotic quark production scenarios.

Phys Rev Lett 98:4 (2007) 041801

Authors:

VM Abazov, B Abbott, M Abolins, BS Acharya, M Adams, T Adams, M Agelou, SH Ahn, M Ahsan, GD Alexeev, G Alkhazov, A Alton, G Alverson, GA Alves, M Anastasoaie, T Andeen, S Anderson, B Andrieu, MS Anzelc, Y Arnoud, M Arov, A Askew, B Asman, ACS Assis Jesus, O Atramentov, C Autermann, C Avila, C Ay, F Badaud, A Baden, L Bagby, B Baldin, DV Bandurin, P Banerjee, S Banerjee, E Barberis, P Bargassa, P Baringer, C Barnes, J Barreto, JF Bartlett, U Bassler, D Bauer, A Bean, M Begalli, M Begel, C Belanger-Champagne, L Bellantoni, A Bellavance, JA Benitez, SB Beri, G Bernardi, R Bernhard, L Berntzon, I Bertram, M Besançon, R Beuselinck, VA Bezzubov, PC Bhat, V Bhatnagar, M Binder, C Biscarat, KM Black, I Blackler, G Blazey, F Blekman, S Blessing, D Bloch, K Bloom, U Blumenschein, A Boehnlein, O Boeriu, TA Bolton, G Borissov, K Bos, T Bose, A Brandt, R Brock, G Brooijmans, A Bross, D Brown, NJ Buchanan, D Buchholz, M Buehler, V Buescher, S Burdin, S Burke, TH Burnett, E Busato, CP Buszello, JM Butler, P Calfayan, S Calvet, J Cammin, S Caron, W Carvalho, BCK Casey, NM Cason, H Castilla-Valdez, D Chakraborty, KM Chan, A Chandra, F Charles, E Cheu, F Chevallier, DK Cho, S Choi, B Choudhary, L Christofek, D Claes, B Clément, C Clément, Y Coadou, M Cooke, WE Cooper, D Coppage, M Corcoran, M-C Cousinou, B Cox, S Crépé-Renaudin, D Cutts, M Cwiok, H da Motta, A Das, M Das, B Davies, G Davies, GA Davis, K De, P de Jong, SJ de Jong, E De La Cruz-Burelo, C De Oliveira Martins, JD Degenhardt, F Déliot, M Demarteau, R Demina, P Demine, D Denisov, SP Denisov, S Desai, HT Diehl, M Diesburg, M Doidge, A Dominguez, H Dong, LV Dudko, L Duflot, SR Dugad, D Duggan, A Duperrin, J Dyer, A Dyshkant, M Eads, D Edmunds, T Edwards, J Ellison, J Elmsheuser, VD Elvira, S Eno, P Ermolov, H Evans, A Evdokimov, VN Evdokimov, SN Fatakia, L Feligioni, AV Ferapontov, T Ferbel, F Fiedler, F Filthaut, W Fisher, HE Fisk, I Fleck, M Ford, M Fortner, H Fox, S Fu, S Fuess, T Gadfort, CF Galea, E Gallas, E Galyaev, C Garcia, A Garcia-Bellido, J Gardner, V Gavrilov, A Gay, P Gay, D Gelé, R Gelhaus, CE Gerber, Y Gershtein, D Gillberg, G Ginther, N Gollub, B Gómez, A Goussiou, PD Grannis, H Greenlee, ZD Greenwood, EM Gregores, G Grenier, Ph Gris, J-F Grivaz, S Grünendahl, MW Grünewald, F Guo, J Guo, G Gutierrez, P Gutierrez, A Haas, NJ Hadley, P Haefner, S Hagopian, J Haley, I Hall, RE Hall, L Han, K Hanagaki, P Hansson, K Harder, A Harel, R Harrington, JM Hauptman, R Hauser, J Hays, T Hebbeker, D Hedin, JG Hegeman, JM Heinmiller, AP Heinson, U Heintz, C Hensel, K Herner, G Hesketh, MD Hildreth, R Hirosky, JD Hobbs, B Hoeneisen, H Hoeth, M Hohlfeld, SJ Hong, R Hooper, P Houben, Y Hu, Z Hubacek, V Hynek, I Iashvili, R Illingworth, AS Ito, S Jabeen, M Jaffré, S Jain, K Jakobs, C Jarvis, A Jenkins, R Jesik, K Johns, C Johnson, M Johnson, A Jonckheere, P Jonsson, A Juste, D Käfer, S Kahn, E Kajfasz, AM Kalinin, JM Kalk, JR Kalk, S Kappler, D Karmanov, J Kasper, P Kasper, I Katsanos, D Kau, R Kaur, R Kehoe, S Kermiche, N Khalatyan, A Khanov, A Kharchilava, YM Kharzheev, D Khatidze, H Kim, TJ Kim, MH Kirby, B Klima, JM Kohli, J-P Konrath, M Kopal, VM Korablev, J Kotcher, B Kothari, A Koubarovsky, AV Kozelov, J Kozminski, D Krop, A Kryemadhi, T Kuhl, A Kumar, S Kunori, A Kupco, T Kurca, J Kvita, S Lammers, G Landsberg, J Lazoflores, A-C Le Bihan, P Lebrun, WM Lee, A Leflat, F Lehner, V Lesne, J Leveque, P Lewis, J Li, QZ Li, JGR Lima, D Lincoln, J Linnemann, VV Lipaev, R Lipton, Z Liu, L Lobo, A Lobodenko, M Lokajicek, A Lounis, P Love, HJ Lubatti, M Lynker, AL Lyon, AKA Maciel, RJ Madaras, P Mättig, C Magass, A Magerkurth, A-M Magnan, N Makovec, PK Mal, HB Malbouisson, S Malik, VL Malyshev, HS Mao, Y Maravin, M Martens, R McCarthy, D Meder, A Melnitchouk, A Mendes, L Mendoza, M Merkin, KW Merritt, A Meyer, J Meyer, M Michaut, H Miettinen, T Millet, J Mitrevski, J Molina, NK Mondal, J Monk, RW Moore, T Moulik, GS Muanza, M Mulders, M Mulhearn, L Mundim, YD Mutaf, E Nagy, M Naimuddin, M Narain, NA Naumann, HA Neal, JP Negret, P Neustroev, C Noeding, A Nomerotski, SF Novaes, T Nunnemann, V O'dell, DC O'neil, G Obrant, V Oguri, N Oliveira, N Oshima, R Otec, GJ Otero Y Garzón, M Owen, P Padley, N Parashar, S-J Park, SK Park, J Parsons, R Partridge, N Parua, A Patwa, G Pawloski, PM Perea, E Perez, K Peters, P Pétroff, M Petteni, R Piegaia, J Piper, M-A Pleier, PLM Podesta-Lerma, VM Podstavkov, Y Pogorelov, M-E Pol, A Pompos, BG Pope, AV Popov, C Potter, WL Prado da Silva, HB Prosper, S Protopopescu, J Qian, A Quadt, B Quinn, MS Rangel, KJ Rani, K Ranjan, PN Ratoff, P Renkel, S Reucroft, M Rijssenbeek, I Ripp-Baudot, F Rizatdinova, S Robinson, RF Rodrigues, C Royon, P Rubinov, R Ruchti, VI Rud, G Sajot, A Sánchez-Hernández, MP Sanders, A Santoro, G Savage, L Sawyer, T Scanlon, D Schaile, RD Schamberger, Y Scheglov, H Schellman, P Schieferdecker, C Schmitt, C Schwanenberger, A Schwartzman, R Schwienhorst, J Sekaric, S Sengupta, H Severini, E Shabalina, M Shamim, V Shary, AA Shchukin, WD Shephard, RK Shivpuri, D Shpakov, V Siccardi, RA Sidwell, V Simak, V Sirotenko, P Skubic, P Slattery, RP Smith, GR Snow, J Snow, S Snyder, S Söldner-Rembold, X Song, L Sonnenschein, A Sopczak, M Sosebee, K Soustruznik, M Souza, B Spurlock, J Stark, J Steele, V Stolin, A Stone, DA Stoyanova, J Strandberg, S Strandberg, MA Strang, M Strauss, R Ströhmer, D Strom, M Strovink, L Stutte, S Sumowidagdo, A Sznajder, M Talby, P Tamburello, W Taylor, P Telford, J Temple, B Tiller, M Titov, VV Tokmenin, M Tomoto, T Toole, I Torchiani, S Towers, T Trefzger, S Trincaz-Duvoid, D Tsybychev, B Tuchming, C Tully, AS Turcot, PM Tuts, R Unalan, L Uvarov, S Uvarov, S Uzunyan, B Vachon, PJ van den Berg, R Van Kooten, WM van Leeuwen, N Varelas, EW Varnes, A Vartapetian, IA Vasilyev, M Vaupel, P Verdier, LS Vertogradov, M Verzocchi, F Villeneuve-Seguier, P Vint, J-R Vlimant, E Von Toerne, M Voutilainen, M Vreeswijk, HD Wahl, L Wang, MHLS Wang, J Warchol, G Watts, M Wayne, M Weber, H Weerts, N Wermes, M Wetstein, A White, D Wicke, GW Wilson, SJ Wimpenny, M Wobisch, J Womersley, DR Wood, TR Wyatt, Y Xie, N Xuan, S Yacoob, R Yamada, M Yan, T Yasuda, YA Yatsunenko, K Yip, HD Yoo, SW Youn, C Yu, J Yu, A Yurkewicz, A Zatserklyaniy, C Zeitnitz, D Zhang, T Zhao, B Zhou, J Zhu, M Zielinski, D Zieminska, A Zieminski, V Zutshi, EG Zverev

Abstract:

We present the first experimental discrimination between the 2e/3 and 4e/3 top quark electric charge scenarios, using top quark pairs (tt) produced in pp collisions at (square root) s = 1.96 TeV by the Fermilab Tevatron Collider. We use 370 pb;{-1} of data collected by the D0 experiment and select events with at least one high transverse momentum electron or muon, high transverse energy imbalance, and four or more jets. We discriminate between b- and b-quark jets by using the charge and momenta of tracks within the jet cones. The data are consistent with the expected electric charge, |q|=2e/3. We exclude, at the 92% C.L., that the sample is solely due to the production of exotic quark pairs QQ with |q|=4e/3. We place an upper limit on the fraction of QQ pairs rho<0.80 at the 90% C.L.

Jet-radius dependence of inclusive-jet cross sections in deep inelastic scattering at HERA

ArXiv hep-ex/0701039 (2007)

Authors:

ZEUS Collaboration, S Chekanov

Impact of and constraints on PDFs at the LHC

15th International Workshop on Deep-Inelastic Scattering and Related Subjects, DIS 2007 (2007)

Abstract:

Uncertainties on parton distribution functions (PDFs) compromise discovery at the LHC for any new physics which can be described as a contact-interaction. PDF uncertainties also limit our ability to use W and Z cross-sections as anaccurate luminosity monitor. The impact of the current level of PDF uncertainty on LHC physics is reviewed and the possibility of reducing this uncertainty using LHC data is investigated.

Measurement of neutral current cross sections at high Bjorken-x with the ZEUS detector at HERA

European Physical Journal C 49:2 (2007) 523-544

Authors:

S Chekanov, M Derrick, S Magill, S Miglioranzi, B Musgrave, D Nicholass, J Repond, R Yoshida, MCK Mattingly, N Pavel, AGY Molina, S Antonelli, P Antonioli, G Bari, M Basile, L Bellagamba, M Bindi, D Boscherini, A Bruni, G Bruni, L Cifarelli, F Cindolo, A Contin, M Corradi, S De Pasquale, G Iacobucci, A Margotti, R Nania, A Polini, L Rinaldi, G Sartorelli, A Zichichi, G Aghuzumtsyan, D Bartsch, I Brock, S Goers, H Hartmann, E Hilger, HP Jakob, M Jüngst, OM Kind, E Paul, J Rautenberg, R Renner, U Samson, V Schönberg, M Wang, M Wlasenko, NH Brook, GP Heath, JD Morris, T Namsoo, M Capua, S Fazio, A Mastroberardino, M Schioppa, G Susinno, E Tassi, JY Kim, KJ Ma, ZA Ibrahim, B Kamaluddin, WAT Wan Abdullah, Y Ning, Z Ren, F Sciulli, J Chwastowski, A Eskreys, J Figiel, A Galas, M Gil, K Olkiewicz, P Stopa, L Zawiejski, L Adamczyk, T Bołd, I Grabowska-Bołd, D Kisielewska, J Łukasik, M Przybycień, L Suszycki, A Kotański, W Słomiński, V Adler, U Behrens, I Bloch, A Bonato, K Borras, N Coppola, J Fourletova, A Geiser, D Gladkov, P Göttlicher, I Gregor, O Gutsche, T Haas, W Hain, C Horn, B Kahle, U Kötz

Abstract:

A new method is employed to measure the neutral current cross section up to Bjorken-x values of one with the ZEUS detector at HERA using an integrated luminosity of 65.1 pb-1 for e+p collisions and 16.7 pb-1 for e-p collisions at √s = 318 GeV and 38.6 pb-1 for e+p collisions at √s = 300 GeV. Cross sections have been extracted for Q2 ≥648 GeV2 and are compared to predictions using different parton density functions. For the highest x bins, the data have a tendency to lie above the expectations using recent parton density function parametrizations. © Springer-Verlag Berlin Heidelberg 2007.

Measurement of prompt photons with associated jets in photoproduction at HERA

European Physical Journal C 49:2 (2007) 511-522

Authors:

S Chekanov, M Derrick, S Magill, S Miglioranzi, B Musgrave, D Nicholass, J Repond, R Yoshida, MCK Mattingly, N Pavel, AG Yagües Molina, S Antonelli, P Antonioli, G Bari, M Basile, L Bellagamba, M Bindi, D Boscherini, A Bruni, G Bruni, L Cifarelli, F Cindolo, A Contin, M Corradi, S De Pasquale, G Iacobucci, A Margotti, R Nania, A Polini, L Rinaldi, G Sartorelli, A Zichichi, G Aghuzumtsyan, D Bartsch, I Brock, S Goers, H Hartmann, E Hilger, HP Jakob, M Jüngst, OM Kind, E Paul, J Rautenberg, R Renner, U Samson, V Schönberg, M Wang, M Wlasenko, NH Brook, GP Heath, JD Morris, T Namsoo, M Capua, S Fazio, A Mastroberardino, M Schioppa, G Susinno, E Tassi, JY Kim, KJ Ma, ZA Ibrahim, B Kamaluddin, WAT Wan Abdullah, Y Ning, Z Ren, F Sciulli, J Chwastowski, A Eskreys, J Figiel, A Galas, M Gil, K Olkiewicz, P Stopa, L Zawiejski, L Adamczyk, T Bołd, I Grabowska-Bołd, D Kisielewska, J Łukasik, M Przybycień, L Suszycki, A Kotański, W Słomiński, V Adler, U Behrens, I Bloch, A Bonato, K Borras, N Coppola, J Fourletova, A Geiser, D Gladkov, P Göttlicher, I Gregor, O Gutsche, T Haas, W Hain, C Horn, B Kahle, U Kötz

Abstract:

The photoproduction of prompt photons, together with an accompanying jet, has been studied in ep collisions at a centre-of-mass energy of 318 GeV with the ZEUS detector at HERA using an integrated luminosity of 77 pb-1. Cross sections were measured for the transverse energy of the photon and the jet larger than 5 and 6 GeV, respectively. The differential γ+jet cross sections were reconstructed as functions of the transverse energy, pseudorapidity and xγobs, the fraction of the incoming photon momentum taken by the photon-jet system. Predictions based on leading-logarithm parton-shower Monte Carlo models and next-to-leading-order (NLO) QCD generally underestimate the cross sections for the transverse energies of prompt photons below 7 GeV, while the kT-factorisation QCD calculation agrees with the data better. When the minimum transverse energy of prompt photons is increased to 7 GeV, both NLO QCD and the kT- factorisation calculations are in good agreement with the data. © Springer-Verlag Berlin Heidelberg 2007.