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Measurement of exclusive ω electroproduction at HERA

Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 487:3-4 (2000) 273-288

Authors:

J Breitweg, S Chekanov, M Derrick, D Krakauer, S Magill, B Musgrave, A Pellegrino, J Repond, R Stanek, R Yoshida, MCK Mattingly, G Abbiendi, F Anselmo, P Antonioli, G Bari, M Basile, L Bellagamba, D Boscherini, A Bruni, G Bruni, G Cara Romeo, G Castellini, L Cifarelli, F Cindolo, A Contin, N Coppola, M Corradi, S de Pasquale, P Giusti, G Iacobucci, G Laurenti, G Levi, A Margotti, T Massam, R Nania, F Palmonari, A Pesci, A Polini, G Sartorelli, Y Zamora Garcia, 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, JD McFall, 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

Abstract:

The exclusive electroproduction of ω mesons, ep → e ω p, has been studied in the kinematic range 3 < Q2 < 20 GeV2, 40 < W < 120 GeV and |t| < 0.6 GeV2 with the ZEUS detector at HERA using an integrated luminosity of 37.7 pb-1. The ω mesons were identified via the decay ω → π+ π- π0. The exclusive cross section in the above kinematic region is σ(ep) → e ω p = 0.108 ± 0.014 (stat.) ± 0.026(syst.) nb. The reaction ep → e φ p, φ → π+ π- π0, has also been measured. The cross sections, as well as the ratios σ γ·p → ωp/σ γ · p → p0p and σ γ · p → ωp/σγ·p → φp, are presented as a function of W and Q2. Thus, for the first time, the properties of ω electroproduction can be compared to those of p0,φ and J/ψ electroproduction at high W. (C) 2000 Elsevier Science B.V.
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Inner-shell soft X-ray lasers in Ne-like ions driven by optical field ionization

Optics Communications 182:1-3 (2000) 209-219

Abstract:

A novel short-wavelength laser based upon monopole excitation of inner-shell electrons in Ne-like ions following optical field ionization with circularly polarized radiation is discussed. Calculations of the small-signal gain are presented for one such ion, Ne-like Ar, for which a small-signal gain of 13.7 cm-1 is predicted on the 2s → 2p hole transition at 15.8 nm for an Ar pressure of 50 mbar. Extensions of this approach to other inner-shell transitions are suggested. © 2000 Elsevier Science B.V. All rights reserved.
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Measurement of the proton structure function F2 at very low Q2 at HERA

Physics Letters B Elsevier 487:1-2 (2000) 53-73

Authors:

ZEUS Collaboration, J Breitweg, S Chekanov, M Derrick, D Krakauer, S Magill, B Musgrave, A Pellegrino, J Repond, R Stanek, R Yoshida, MCK Mattingly, G Abbiendi, F Anselmo, P Antonioli, G Bari, M Basile, L Bellagamba, D Boscherini, A Bruni, G Bruni, G Cara Romeo, G Castellini, L Cifarelli, F Cindolo, A Contin, N Coppola, M Corradi, S De Pasquale, P Giusti, G Iacobucci, G Laurenti, G Levi, A Margotti, T Massam, R Nania, F Palmonari, A Pesci, A Polini, G Sartorelli, Y Zamora Garcia, A Zichichi, C Amelung, A Bornheim, I Brock, K Coböken, J Crittenden, R Deffner, H Hartmann, K Heinloth, E Hilger, P Irrgang, H-P Jakob, A Kappes, UF Katz, R Kerger, E Paul, H Schnurbusch, A Stifutkin, J Tandler, KC Voss, A Weber, H Wieber, DS Bailey, O Barret, NH Brook, B Foster, GP Heath, HF Heath, JD McFall, D Piccioni, 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, M Przybycień, E Rulikowska-Zarȩbska, L Suszycki, D Szuba, A Kotański, LAT Bauerdick, U Behrens, JK Bienlein, C Burgard, D Dannheim, K Desler, G Drews, A Fox-Murphy, U Fricke, F Goebel, P Göttlicher, R Graciani, T Haas, W Hain, GF Hartner, D Hasell, K Hebbel, KF Johnson, M Kasemann, W Koch, U Kötz, H Kowalski, L Lindemann, B Löhr, M Martı́nez, M Milite, T Monteiro, M Moritz, D Notz, F Pelucchi, MC Petrucci, M Rohde, PRB Saull, AA Savin, U Schneekloth, F Selonke, M Sievers, S Stonjek, E Tassi, G Wolf, U Wollmer, C Youngman, W Zeuner, C Coldewey, A Lopez-Duran Viani, A Meyer, S Schlenstedt, PB Straub, G Barbagli, E Gallo, P Pelfer, G Maccarrone, L Votano, A Bamberger, A Benen, S Eisenhardt, P Markun, H Raach, S Wölfle, PJ Bussey, M Bell, AT Doyle, SW Lee, A Lupi, N Macdonald, GJ McCance, DH Saxon, LE Sinclair, IO Skillicorn, R Waugh, I Bohnet, N Gendner, U Holm, A Meyer-Larsen, H Salehi, K Wick, A Garfagnini, I Gialas, LK Gladilin, D Kçira, R Klanner, E Lohrmann, G Poelz, F Zetsche, R Goncalo, KR Long, DB Miller, AD Tapper, R Walker, U Mallik, P Cloth, D Filges, T Ishii, M Kuze, K Nagano, K Tokushuku, S Yamada, Y Yamazaki, SH Ahn, SB Lee, SK Park, H Lim, IH Park, D Son, F Barreiro, G Garcı́a, C Glasman, O González, L Labarga, J del Peso, I Redondo, J Terrón, M Barbi, F Corriveau, DS Hanna, A Ochs, S Padhi, M Riveline, DG Stairs, M Wing, T Tsurugai, A Antonov, V Bashkirov, M Danilov, BA Dolgoshein, D Gladkov, V Sosnovtsev, S Suchkov, RK Dementiev, PF Ermolov, Yu A Golubkov, II Katkov, LA Khein, NA Korotkova, IA Korzhavina, VA Kuzmin, O Yu Lukina, AS Proskuryakov, LM Shcheglova, AN Solomin, NN Vlasov, SA Zotkin, C Bokel, M Botje, N Brümmer, J Engelen, S Grijpink, E Koffeman, P Kooijman, S Schagen, A van Sighem, H Tiecke, N Tuning, JJ Velthuis, J Vossebeld, L Wiggers, E de Wolf, D Acosta, B Bylsma, LS Durkin, J Gilmore, CM Ginsburg, CL Kim, TY Ling, S Boogert, AM Cooper-Sarkar, RCE Devenish, J Große-Knetter, T Matsushita, A Quadt, O Ruske, MR Sutton, R Walczak, A Bertolin, R Brugnera, R Carlin, F Dal Corso, U Dosselli, S Dusini, S Limentani, M Morandin, M Posocco, L Stanco, R Stroili, M Turcato, C Voci, L Adamczyk, L Iannotti, BY Oh, JR Okrasiński, WS Toothacker, JJ Whitmore, Y Iga, G D'Agostini, G Marini, A Nigro, C Cormack, JC Hart, NA McCubbin, TP Shah, D Epperson, C Heusch, HF-W Sadrozinski, A Seiden, R Wichmann, DC Williams, N Pavel, H Abramowicz, S Dagan, S Kananov, A Kreisel, A Levy, T Abe, T Fusayasu, K Umemori, T Yamashita, R Hamatsu, T Hirose, M Inuzuka, S Kitamura, T Nishimura, M Arneodo, N Cartiglia, R Cirio, M Costa, MI Ferrero, S Maselli, V Monaco, C Peroni, M Ruspa, R Sacchi, A Solano, A Staiano, M Dardo, DC Bailey, C-P Fagerstroem, R Galea, T Koop, GM Levman, JF Martin, RS Orr, S Polenz, A Sabetfakhri, D Simmons, JM Butterworth, CD Catterall, ME Hayes, EA Heaphy, TW Jones, JB Lane, BJ West, J Ciborowski, R Ciesielski, G Grzelak, RJ Nowak, JM Pawlak, R Pawlak, B Smalska, T Tymieniecka, AK Wróblewski, JA Zakrzewski, AF Żarnecki, M Adamus, T Gadaj, O Deppe, Y Eisenberg, D Hochman, U Karshon, WF Badgett, D Chapin, R Cross, C Foudas, S Mattingly, DD Reeder, WH Smith, A Vaiciulis, T Wildschek, M Wodarczyk, A Deshpande, S Dhawan, VW Hughes, S Bhadra, C Catterall, JE Cole, WR Frisken, R Hall-Wilton, M Khakzad, S Menary
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Measurement of azimuthal asymmetries in deep inelastic scattering

Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 481:2-4 (2000) 199-212

Authors:

J Breitweg, S Chekanov, M Derrick, D Krakauer, S Magill, B Musgrave, A Pellegrino, J Repond, R Stanek, R Yoshida, MCK Mattingly, G Abbiendi, F Anselmo, P Antonioli, G Bari, M Basile, L Bellagamba, D Boscherini, A Bruni, G Bruni, G Cara Romeo, G Castellini, L Cifarelli, F Cindolo, A Contin, N Coppola, M Corradi, S de Pasquale, P Giusti, G Iacobucci, G Laurenti, G Levi, A Margotti, T Massam, R Nania, F Palmonari, A Pesci, A Polini, G Sartorelli, Y Zamora Garcia, 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, H Schnurbusch, A Stifutkin, J Tandler, KC Voss, A Weber, H Wieber, DS Bailey, O Barret, NH Brook, B Foster, GP Heath, HF Heath, JD McFall, D Piccioni, 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

Abstract:

The distribution of the azimuthal angle for the charged hadrons has been studied in the hadronic centre-of-mass system for neutral current deep inelastic positron-proton scattering with the ZEUS detector at HERA. Measurements of the dependence of the moments of this distribution on the transverse momenta of the charged hadrons are presented. Asymmetries that can be unambiguously attributed to perturbative QCD processes have been observed for the first time. (C) 2000 Elsevier Science B.V.
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Measurement of inclusive(D(s)(±)) photoproduction at HERA ZEUS collaboration

Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics 481:2-4 (2000) 213-227

Authors:

J Breitweg, S Chekanov, M Derrick, D Krakauer, S Magill, B Musgrave, A Pellegrino, J Repond, R Stanek, R Yoshida, MCK Mattingly, G Abbiendi, F Anselmo, P Antonioli, G Bari, M Basile, L Bellagamba, D Boscherini, A Bruni, G Bruni, G Cara Romeo, G Castellini, L Cifarelli, F Cindolo, A Contin, N Coppola, M Corradi, S de Pasquale, P Giusti, G Iacobucci, G Laurenti, G Levi, A Margotti, T Massam, R Nania, F Palmonari, A Pesci, A Polini, G Sartorelli, Y Zamora Garcia, 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, H Schnurbusch, A Stifutkin, J Tandler, KC Voss, A Weber, H Wieber, DS Bailey, O Barret, NH Brook, B Foster, GP Heath, HF Heath, JD McFall, D Piccioni, 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

Abstract:

The first measurement of inclusive D(s)(±) photoproduction at HERA has been performed with the ZEUS detector for photon-proton centre-of-mass energies 130 < W < 280GeV. The measured cross section for 3 < p (is perpendicular to)/(D(s)) < 12GeV and |η(D(s))| < 1.5 is σ(ep → D(s)X) = 3.79 ± 0.59(stat.) -0.46/+0.26 (syst.) ± 0.94(br.)nb, where the last error arises from the uncertainty in the D(s)(±) decay branching ratio. The measurements are compared with inclusive D*(±) photoproduction cross sections in the same kinematic region and with QCD calculations. The D(s)(±) cross sections lie above a fixed-order next-to-leading order calculation and agree better with a tree-level O(αα(s)/3) calculation that was tuned to describe the ZEUS D*(±) cross sections. The ratio of D(s)(±) to D*(±) cross sections is 0.41 ± 0.07 (stat.) -0.05/+0.03 (syst.) ± 0.10(br.). From this ratio, the strangeness-suppression factor in charm photoproduction, within the LUND string fragmentation model, has been calculated to be γ(s) = 0.27 ± 0.05 ± 0.07(br.). The cross-section ratio and γ(s) are in good agreement with those obtained in charm production in e+e- annihilation. (C) 2000 Elsevier Science B.V.
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