Prof Roman Walczak: Publications

Measurement of the longitudinal proton structure function at HERA

Physics Letters Section B Nuclear Elementary Particle and High Energy Physics 682:1 (2009) 8-22

Authors:

Abstract:

The reduced cross sections for ep deep inelastic scattering have been measured with the ZEUS detector at HERA at three different centre-of-mass energies, 318, 251 and 225 GeV. From the cross sections, measured double differentially in Bjorken x and the virtuality, Q ², the proton structure functions F L and F 2 have been extracted in the region 5 × 10 ^{- 4} < x < 0.007 and 20 < Q ² < 130 GeV ². © 2009 Elsevier B.V.

Scaled momentum distributions of charged particles in dijet photoproduction at HERA

Journal of High Energy Physics 2009:8 (2009)

Authors:

O Behnke, J Behr, U Behrens, C Blohm, K Borras, D Bot, R Ciesielski, N Coppola, S Fang, A Geiser, P Gölttlicher, J Grebenyuk, I Gregor, T Haas, W Hain, A Hüttmann, F Januschek, B Kahle, II Katkov, U Klein, U Kötz, H Kowalski, M Lisovyi, E Lobodzinska, B Löhr, R Mankel, IA Melzer-Pellmann, S Miglioranzi, A Montanari, T Namsoo, D Notz, A Parenti, P Roloff, I Rubinsky, U Schneekloth, A Spiridonov, D Szuba, J Szuba, T Theedt, J Tomaszewska, G Wolf, K Wrona, AG Yagües-Molina, C Youngman, W Zeuner, S Chekanov, M Derrick, S Magill, B Musgrave, D Nicholass, J Repond, R Yoshida, MCK Mattingly, P Antonioli, G Bari, L Bellagamba, D Boscherini, A Bruni, G Bruni, F Cindolo, M Corradi, G Iacobucci, A Margotti, R Nania, A Polini, S Antonelli, M Basile, M Bindi, L Cifarelli, A Contin, S De Pasquale, G Sartorelli, A Zichichi, D Bartsch, I Brock, H Hartmann, E Hilger, HP Jakob, M Jüngst, AE Nuncio-Quiroz, E Paul, U Samson, V Schönberg, R Shehzadi, M Wlasenko, NH Brook, GP Heath, JD Morris, M Kaur, P Kaur, I Singh, M Capua, S Fazio, A Mastroberardino, M Schioppa, G Susinno, E Tassi, JY Kim, ZA Ibrahim, F Mohamad Idris

Abstract:

The scaled momentum distributions of charged particles in jets have been measured for dijet photoproduction with the ZEUS detector at HERA using an integrated luminosity of 359 pb^-1. The distributions are compared to predictions based on perturbative QCD carried out in the framework of the modified leading-logarithmic approximation (MLLA) and assuming local parton-hadron duality (LPHD). The universal MLLA scale, Λeff, and the LPHD parameter, κ^ch, are extracted. © SISSA 2009.

Subjet distributions in deep inelastic scattering at HERA

European Physical Journal C 63:4 (2009) 527-548

Authors:

Abstract:

Subjet distributions were measured in neutral current deep inelastic ep scattering with the ZEUS detector at HERA using an integrated luminosity of 81.7 pb-1. Jets were identified using the k T cluster algorithm in the laboratory frame. Subjets were defined as jet-like substructures identified by a reapplication of the cluster algorithm at a smaller value of the resolution parameter ycut. Measurements of subjet distributions for jets with exactly two subjets for ycut=0.05 are presented as functions of observables sensitive to the pattern of parton radiation and to the colour coherence between the initial and final states. Perturbative QCD predictions give an adequate description of the data. © 2009 Springer-Verlag / Società Italiana di Fisica.

Measurement of D (+/-) and D (0) production in deep inelastic scattering using a lifetime tag at HERA

EUR PHYS J C 63:3 (2009) 171-188

Authors:

S Chekanov, M Derrick, S Magill, B Musgrave, D Nicholass, J Repond, R Yoshida, MCK Mattingly, P Antonioli, G Bari, L Bellagamba, D Boscherini, A Bruni, G Bruni, F Cindolo, M Corradi, G Iacobucci, A Margotti, R Nania, A Polini, S Antonelli, M Basile, M Bindi, L Cifarelli, A Contin, S De Pasquale, G Sartorelli, A Zichichi, D Bartsch, I Brock, H Hartmann, E Hilger, HP Jakob, M Jungst, AE Nuncio-Quiroz, E Paul, U Samson, V Schonberg, R Shehzadi, M Wlasenko, NH Brook, GP Heath, JD Morris, M Kaur, P Kaur, I Singh, M Capua, S Fazio, A Mastroberardino, M Schioppa, G Susinno, E Tassi, JY Kim, ZA Ibrahim, F Idris, B Kamaluddin, WATW Abdullah, Y Ning, Z Ren, F Sciulli, J Chwastowski, A Eskreys, J Figiel, A Galas, K Olkiewicz, B Pawlik, P Stopa, L Zawiejski, L Adamczyk, T Bold, I Grabowska-Bold, D Kisielewska, J Laukasik, M Przybycien, L Suszycki, A Kotanski, W Sominski, O Behnke, U Behrens, C Blohm, A Bonato, K Borras, D Bot, R Ciesielski, N Coppola, S Fang, J Fourletova, A Geiser, P Gottlicher, J Grebenyuk, I Gregor, T Haas, W Hain, A Huttmann, F Januschek, B Kahle, II Katkov, U Klein, U Kotz, H Kowalski, M Lisovyi, E Lobodzinska, B Lohr, R Mankel, IA Melzer-Pellmann, S Miglioranzi, A Montanari, T Namsoo, D Notz, A Parenti, L Rinaldi, P Roloff, I Rubinsky, U Schneekloth, A Spiridonov, D Szuba, J Szuba, T Theedt, J Ukleja, G Wolf, K Wrona, AGY Molina, C Youngman, W Zeuner, V Drugakov, W Lohmann, S Schlenstedt, G Barbagli, E Gallo, PG Pelfer, A Bamberger, D Dobur, F Karstens, NN Vlasov, PJ Bussey, AT Doyle, W Dunne, M Forrest, M Rosin, DH Saxon, IO Skillicorn, I Gialas, K Papageorgiu, U Holm, R Klanner, E Lohrmann, H Perrey, P Schleper, T Schorner-Sadenius, J Sztuk, H Stadie, M Turcato, C Foudas, C Fry, KR Long, AD Tapper, T Matsumoto, K Nagano, K Tokushuku, S Yamada, Y Yamazaki, AN Barakbaev, EG Boos, NS Pokrovskiy, BO Zhautykov, V Aushev, O Bachynska, M Borodin, I Kadenko, A Kozulia, V Libov, D Lontkovskyi, I Makarenko, I Sorokin, A Verbytskyi, O Volynets, D Son, J de Favereau, K Piotrzkowski, F Barreiro, C Glasman, M Jimenez, L Labarga, J del Peso, E Ron, M Soares, J Terron, C Uribe-Estrada, M Zambrana, F Corriveau, C Liu, J Schwartz, R Walsh, C Zhou, T Tsurugai, A Antonov, BA Dolgoshein, D Gladkov, V Sosnovtsev, A Stifutkin, S Suchkov, RK Dementiev, PF Ermolov, LK Gladilin, YA Golubkov, LA Khein, IA Korzhavina, VA Kuzmin, BB Levchenko, OY Lukina, AS Proskuryakov, LM Shcheglova, DS Zotkin, I Abt, A Caldwell, D Kollar, B Reisert, WB Schmidke, G Grigorescu, A Keramidas, E Koffeman, P Kooijman, A Pellegrino, H Tiecke, M Vazquez, L Wiggers, N Brummer, B Bylsma, LS Durkin, A Lee, TY Ling, PD Allfrey, MA Bell, AM Cooper-Sarkar, RCE Devenish, J Ferrando, B Foster, C Gwenlan, K Horton, K Oliver, A Robertson, R Walczak, A Bertolin, F Dal Corso, S Dusini, A Longhin, L Stanco, P Bellan, R Brugnera, R Carlin, A Garfagnini, S Limentani, BY Oh, A Raval, JJ Whitmore, Y Iga, G D'Agostini, G Marini, A Nigro, JE Cole, JC Hart, H Abramowicz, R Ingbir, S Kananov, A Levy, A Stern, M Kuze, J Maeda, R Hori, S Kagawa, N Okazaki, S Shimizu, T Tawara, R Hamatsu, H Kaji, S Kitamura, O Ota, YD Ri, M Costa, MI Ferrero, V Monaco, R Sacchi, V Sola, A Solano, M Arneodo, M Ruspa, S Fourletov, JF Martin, TP Stewart, SK Boutle, JM Butterworth, R Hall-Wilton, TW Jones, JH Loizides, MR Sutton, M Wing, B Brzozowska, J Ciborowski, G Grzelak, P Kulinski, P Luzniak, J Malka, RJ Nowak, JM Pawlak, W Perlanski, T Tymieniecka, AF Zarnecki, M Adamus, P Plucinski, A Ukleja, Y Eisenberg, D Hochman, U Karshon, E Brownson, DD Reeder, AA Savin, WH Smith, H Wolfe, S Bhadra, CD Catterall, Y Cui, G Hartner, S Menary, U Noor, J Standage, J Whyte, ZEUS Collaboration

Abstract:

The production of D-+/-- and D-0-mesons has been measured with the ZEUS detector at HERA using an integrated luminosity of 133.6 pb(-1). The measurements cover the kinematic range 5 < Q(2) < 1000 GeV2, 0.02 < y < 0.7, 1.5 < p(T)(D) < 15 GeV and |eta(D)| < 1.6. Combinatorial background to the D-meson signals is reduced by using the ZEUS microvertex detector to reconstruct displaced secondary vertices. Production cross sections are compared with the predictions of next-to-leading-order QCD, which is found to describe the data well. Measurements are extrapolated to the full kinematic phase space in order to obtain the open-charm contribution, F-2(c (c) over bar), to the proton structure function, F-2.

Exclusive photoproduction of ϒmesons at HERA

Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 680:1 (2009) 4-12

Authors:

S Chekanov, M Derrick, S Magill, B Musgrave, D Nicholass, J Repond, R Yoshida, MCK Mattingly, P Antonioli, G Bari, L Bellagamba, D Boscherini, G Bruni, F Cindolo, M Corradi, G Iacobucci, A Margotti, R Nania, A Polini, S Antonelli, M Basile, M Bindi, L Cifarelli, A Contin, S De Pasquale, G Sartorelli, A Zichichi, D Bartsch, I Brock, H Hartmann, E Hilger, HP Jakob, M Jüngst, AE Nuncio-Quiroz, E Paul, U Samson, V Schönberg, R Shehzadi, M Wlasenko, NH Brook, GP Heath, JD Morris, M Kaur, P Kaur, I Singh, M Capua, S Fazio, A Mastroberardino, M Schioppa, G Susinno, E Tassi, JY Kim, ZA Ibrahim, FM Idris, B Kamaluddin, WAT Wan Abdullah, Y Ning, Z Ren, F Sciulli, J Chwastowski, A Eskreys, J Figiel, A Galas, K Olkiewicz, B Pawlik, P Stopa, L Zawiejski, L Adamczyk, T Bołd, I Grabowska-Bołd, D Kisielewska, J Łukasik, M Przybycień, L Suszycki, A Kotański, W Słomiński, O Behnke, J Behr, U Behrens, C Blohm, K Borras, D Bot, R Ciesielski, N Coppola, S Fang, A Geiser, P Göttlicher, J Grebenyuk, I Gregor, T Haas, W Hain, A Hüttmann, F Januschek, B Kahle, II Katkov, U Klein, U Kötz, H Kowalski, M Lisovyi, E Lobodzinska

Abstract:

The exclusive photoproduction reaction γ p → Υ{hooked} p has been studied with the ZEUS experiment in ep collisions at HERA using an integrated luminosity of 468 pb-1. The measurement covers the kinematic range 60 < W < 220 GeV and Q2 < 1 GeV2, where W is the photon-proton centre-of-mass energy and Q2 is the photon virtuality. These results, which represent the analysis of the full ZEUS data sample for this channel, are compared to predictions based on perturbative QCD. © 2009 Elsevier B.V.

51��