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Jet cross sections and αs in deep inelastic scattering and photoproduction at hera

DIS 2009 - Proceedings of the 17th International Workshop on Deep-Inelastic Scattering and Related Topics (2009)

Abstract:

Recent ZEUS measurements of inclusive-jet and dijet cross sections in neutral current deep inelastic ep scattering at HERA are presented. The data correspond to more than a two-fold increase in statistics compared to previous studies. The cross sections are measured in the Breit frame, for boson virtualities of Q2 > 125 GeV2, as functions of various kinematic and jet observables. The data are found to be well described by NLO QCD and have the potential to constrain the gluon density in the proton. Two new extractions of the strong coupling, αs, are also presented: the first is determined from the inclusive-jet neutral current DIS measurement presented here, while the second is from a re-analysis of previously published data on inclusive jet photoproduction. Both measurements are of competitive precision and in agreement with the world average.
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Jet cross sections and α s in deep inelastic scattering and photoproduction at HERA

ScienceWise Publishing (2009)
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Leading proton production in deep inelastic scattering at HERA

Journal of High Energy Physics 2009:6 (2009)

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, G Cara Romeo, F Cindolo, M Corradi, P Giusti, G Iacobucci, A Margotti, T Massam, R Nania, A Polini, S Antonelli, M Basile, M Bindi, L Cifarelli, A Contin, F Palmonari, 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, L Ianotti, A Mastroberardino, M Schioppa, G Susinno, E Tassi, JY Kim, ZA Ibrahim, F Mohamad 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 Lukasik, M Przybycień, L Suszycki, A Kotański, W Slomiński, O Behnke, U Behrens, C Blohm, A Bonato, K Borras, D Bot, R Ciesielski, N Coppola, S Fang, J Fourletova, A Geiser, P Göttlicher, J Grebenyuk, I Gregor, T Haas, W Hain, A Hüttmann, F Januschek

Abstract:

The semi-inclusive reaction e+p→e+Xp was studied with the ZEUS detector at HERA with an integrated luminosity of 12.8 pb -1. The final-state proton, which was detected with the ZEUS leading proton spectrometer, carried a large fraction of the incoming proton energy, xL > 0.32, and its transverse momentum squared satisfied p 2T < 0.5GeV2; the exchanged photon virtuality, Q2, was greater than 3GeV2 and the range of the masses of the photon-proton system was 45 < W < 225GeV. The leading proton production cross section and rates are presented as a function of xL, p2 T , Q2 and the Bjorken scaling variable, x. © SISSA 2009.
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Measurement of beauty photoproduction using decays into muons in dijet events at HERA

Journal of High Energy Physics 2009:4 (2009)

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, 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, U Behrens, C Blohm, A Bonato, K Borras, D Bot, R Ciesielski, N Coppola, S Fang, J Fourletova, 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

Abstract:

Beauty photoproduction in dijet events has been measured at HERA with the ZEUS detector using an integrated luminosity of 126 pb-1. Beauty was identified in events with a muon in the final state by using the transverse momentum of the muon relative to the closest jet. Lifetime information from the silicon vertex detector was also used; the impact parameter of the muon with respect to the primary vertex was exploited to discriminate between signal and background. Cross sections for beauty production as a function of the muon and the jet variables as well as dijet correlations are compared to QCD predictions and to previous measurements. The data are well described by predictions from next-to-leading-order QCD. © SISSA 2009.
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Measurement of the charm fragmentation function in D* photoproduction at HERA

Journal of High Energy Physics 2009:4 (2009)

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, 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, U Behrens, C Blohm, A Bonato, K Borras, D Bot, R Ciesielski, N Coppola, S Fang, J Fourletova, 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

Abstract:

The charm fragmentation function has been measured in D* photoproduction with the ZEUS detector at HERA using an integrated luminosity of 120 pb-1. The fragmentation function is measured versus z = (E +p||)D* /2Ejet, where E is the energy of the D * meson and p|| is the longitudinal momentum of the D * meson relative to the axis of the associated jet of energy Ejet. Jets were reconstructed using the kT clustering algorithm and required to have transverse energy larger than 9GeV. The D* meson associated with the jet was required to have a transverse momentum larger than 2GeV. The measured function is compared to different fragmentation models incorporated in leading-logarithm Monte Carlo simulations and in a next-to-leading-order QCD calculation. The free parameters in each fragmentation model are fitted to the data. The extracted parameters and the function itself are compared to measurements from e+e-experiments. © SISSA 2009.
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