Prof Roman Walczak: Publications

Events with an isolated lepton and missing transverse momentum and measurement of W production at HERA

Journal of High Energy Physics 2010:3 (2010)

Authors:

FD Aaron, H Abramowicz, I Abt, L Adamczyk, M Adamus, M Aldaya Martin, C Alexa, V Andreev, S Antonelli, P Antonioli, A Antonov, B Antunovic, M Arneodo, V Aushev, O Bachynska, S Backovic, A Baghdasaryan, A Bamberger, AN Barakbaev, G Barbagli, G Bari, F Barreiro, E Barrelet, W Bartel, D Bartsch, M Basile, K Begzsuren, O Behnke, J Behr, U Behrens, L Bellagamba, A Belousov, A Bertolin, S Bhadra, M Bindi, JC Bizot, C Blohm, T Bołd, EG Boos, M Borodin, K Borras, D Boscherini, D Bot, V Boudry, SK Boutle, I Bozovic-Jelisavcic, J Bracinik, G Brandt, M Brinkmann, V Brisson, I Brock, E Brownson, R Brugnera, N Brümmer, D Bruncko, A Bruni, G Bruni, B Brzozowska, A Bunyatyan, G Buschhorn, PJ Bussey, JM Butterworth, B Bylsma, L Bystritskaya, A Caldwell, AJ Campbell, KB Cantun Avila, M Capua, R Carlin, CD Catterall, K Cerny, V Cerny, S Chekanov, V Chekelian, A Cholewa, J Chwastowski, J Ciborowski, R Ciesielski, L Cifarelli, F Cindolo, A Contin, JG Contreras, AM Cooper-Sarkar, N Coppola, M Corradi, F Corriveau, M Costa, JA Coughlan, G Cozzika, J Cvach, G D’Agostini, JB Dainton, F Dal Corso, K Daum, M Deák, J de Favereau, B Delcourt, M Del Degan, J del Peso, J Delvax

Abstract:

A search for events containing an isolated electron or muon and missing transverse momentum produced in e±p collisions is performed with the H1 and ZEUS detectors at HERA. The data were taken in the period 1994-2007 and correspond to an integrated luminosity of 0.98 fb-1. The observed event yields are in good overall agreement with the Standard Model prediction, which is dominated by single W production. In the e+p data, at large hadronic transverse momentum PTX < 25GeV, a total of 23 events are observed compared to a prediction of 14.0 ±1.9. The total single W boson production cross section is measured as 1.06 ± 0.16 (stat.) ± 0.07 (sys.) pb, in agreement with an Standard Model (SM) expectation of 1.26 ± 0.19 pb.

Measurement of D⁺ and Λc⁺ production in deep inelastic scattering at HERA

Journal of High Energy Physics 2010:11 (2010)

Authors:

H Abramowicz, I Abt, L Adamczyk, M Adamus, R Aggarwal, S Antonelli, P Antonioli, A Antonov, M Arneodo, V Aushev, Y Aushev, O Bachynska, A Bamberger, AN Barakbaev, G Barbagli, G Bari, F Barreiro, D Bartsch, M Basile, O Behnke, J Behr, U Behrens, L Bellagamba, A Bertolin, S Bhadra, M Bindi, C Blohm, T Bołd, EG Boos, M Borodin, K Borras, D Boscherini, D Bot, SK Boutle, I Brock, E Brownson, R Brugnera, N Brümmer, A Bruni, G Bruni, B Brzozowska, PJ Bussey, JM Butterworth, B Bylsma, A Caldwell, M Capua, R Carlin, CD Catterall, S Chekanov, J Chwastowski, J Ciborowski, R Ciesielski, L Cifarelli, F Cindolo, A Contin, AM Cooper-Sarkar, N Coppola, M Corradi, F Corriveau, M Costa, G D'Agostini, F Dal Corso, J De Favereau, J Del Peso, RK Dementiev, S De Pasquale, M Derrick, RCE Devenish, D Dobur, BA Dolgoshein, AT Doyle, V Drugakov, LS Durkin, S Dusini, Y Eisenberg, PF Ermolov, A Eskreys, S Fang, S Fazio, J Ferrando, MI Ferrero, J Figiel, M Forrest, B Foster, S Fourletov, G Gach, A Galas, E Gallo, A Garfagnini, A Geiser, I Gialas, LK Gladilin, D Gladkov, C Glasman, O Gogota, YA Golubkov, P Göttlicher, I Grabowska-Bołd, J Grebenyuk, I Gregor

Abstract:

Charm production in deep inelastic scattering has been measured with the ZEUS detector at HERA using an integrated luminosity of 120 pb-1. The hadronic decay channels D+ → KS0π+, Λc+ → pKS0 and Λc+ → Λπ+, and their charge conjugates, were reconstructed. The presence of a neutral strange hadron in the final state reduces the combinatorial background and extends the measured sensitivity into the low transverse momentum region. The kinematic range is 0 < pT (D+,Λc+ ) < 10GeV, |η(D+,Λc+ )| < 1.6, 1.5 < Q2 < 1000GeV2 and 0.02 < y < 0.7. Inclusive and differential cross sections for the production of D+ mesons are compared to next-to-leading-order QCD predictions. The fraction of c quarks hadronising into Λc+ baryons is extracted.

Measurement of J/ψ photoproduction at large momentum transfer at HERA

Journal of High Energy Physics 2010:5 (2010)

Authors:

S Chekanov, M Derrick, S Magill, B Musgrave, D Nicholass, J Repond, R Yoshida, 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 Jüingst, AE Nuncio-Quiroz, E Paul, U Samson, V Schönberg, R Shehzadi, M Wlasenko, 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 Bachynska, 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, V Libov, M Lisovyi, E Lobodzinska

Abstract:

The proton-dissociative diffractive photoproduction of J/ψ mesons has been studied in ep collisions with the ZEUS detector at HERA using an integrated luminosity of 112 pb-1. The cross section is presented as a function of the photon-proton centre-ofmass energy and of the squared four-momentum transfer at the proton vertex. The results are compared to perturbative QCD calculations.

Measurement of charm and beauty production in deep inelastic ep scattering from decays into muons at HERA

European Physical Journal C 65:1 (2010) 65-79

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 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, 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 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

Abstract:

The production of charm and beauty quarks in ep interactions has been measured with the ZEUS detector at HERA for squared four-momentum exchange Q2>20 GeV2, using an integrated luminosity of 126 pb-1. Charm and beauty quarks were identified through their decays into muons. Differential cross sections were measured for muon transverse momenta pTμ> 1.5 GeV and pseudorapidities -1. 6<ημ>2. 3, as a function of pTμ>, ημ, Q2and Bjorken x. The charm and beauty contributions to the proton structure function F2were also extracted. The results agree with previous measurements based on independent techniques and are well described by QCD predictions. © Springer-Verlag / Società Italiana di Fisica 2009.

Scaled momentum spectra in deep inelastic scattering at HERA

Journal of High Energy Physics 2010:6 (2010)

Authors:

H Abramowicz, I Abt, L Adamczyk, M Adamus, S Antonelli, P Antonioli, A Antonov, M Arneodo, V Aushev, Y Aushev, O Bachynska, A Bamberger, AN Barakbaev, G Barbagli, G Bari, F Barreiro, D Bartsch, M Basile, O Behnke, J Behr, U Behrens, L Bellagamba, A Bertolin, S Bhadra, M Bindi, C Blohm, T Bołd, G Boos, M Borodin, K Borras, D Boscherini, D Bot, SK Boutle, I Brock, E Brownson, R Brugnera, N Brümmer, A Bruni, G Bruni, B Brzozowska, PJ Bussey, JM Butterworth, B Bylsma, A Caldwell, M Capua, R Carlin, CD Catterall, S Chekanov, J Chwastowski, J Ciborowski, R Ciesielski, L Cifarelli, F Cindolo, A Contin, AM Cooper-Sarkar, N Coppola, M Corradi, F Corriveau, M Costa, G D'Agostini, F Dal Corso, J De Favereau, J Del Peso, RK Dementiev, S De Pasquale, M Derrick, RCE Devenish, D Dobur, BA Dolgoshein, AT Doyle, V Drugakov, LS Durkin, S Dusini, Y Eisenberg, PF Ermolov, A Eskreys, S Fang, S Fazio, J Ferrando, MI Ferrero, J Figiel, M Forrest, S Fourletov, A Galas, E Gallo, A Garfagnini, A Geiser, I Gialas, LK Gladilin, D Gladkov, C Glasman, O Gogota, YA Golubkov, P Göttlicher, I Grabowska-Bołd, J Grebenyuk, I Gregor, G Grigorescu, G Grzelak, C Gwenlan

Abstract:

Charged particle production has been studied in neutral current deep inelastic ep scattering with the ZEUS detector at HERA using an integrated luminosity of 0.44 fb?1. Distributions of scaled momenta in the Breit frame are presented for particles in the current fragmentation region. The evolution of these spectra with the photon virtuality, Q2, is described in the kinematic region 10 < Q2< 41000Ge V2. Next-to-leading-order and modified leading-log-approximation QCD calculations as well as predictions from Monte Carlo models are compared to the data. The results are also compared to e+e? annihilation data. The dependences of the pseudorapidity distribution of the particles on Q2 and on the energy in the p system, W, are presented and interpreted in the context of the hypothesis of limiting fragmentation.

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