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Observation and mass measurement of the baryon Ξb-

Physical Review Letters 99:5 (2007)

Authors:

T Aaltonen, A Abulencia, J Adelman, T Affolder, T Akimoto, MG Albrow, S Amerio, D Amidei, A Anastassov, K Anikeev, A Annovi, J Antos, M Aoki, G Apollinari, T Arisawa, A Artikov, W Ashmanskas, A Attal, A Aurisano, F Azfar, P Azzi-Bacchetta, P Azzurri, N Bacchetta, W Badgett, A Barbaro-Galtieri, VE Barnes, BA Barnett, S Baroiant, V Bartsch, G Bauer, PH Beauchemin, F Bedeschi, S Behari, G Bellettini, J Bellinger, A Belloni, D Benjamin, A Beretvas, J Beringer, T Berry, A Bhatti, M Binkley, D Bisello, I Bizjak, RE Blair, C Blocker, B Blumenfeld, A Bocci, A Bodek, V Boisvert, G Bolla, A Bolshov, D Bortoletto, J Boudreau, A Boveia, B Brau, L Brigliadori, C Bromberg, E Brubaker, J Budagov, HS Budd, S Budd, K Burkett, G Busetto, P Bussey, A Buzatu, KL Byrum, S Cabrera, M Campanelli, M Campbell, F Canelli, A Canepa, S Carrillo, D Carlsmith, R Carosi, S Carron, B Casal, M Casarsa, A Castro, P Catastini, D Cauz, M Cavalli-Sforza, A Cerri, L Cerrito, SH Chang, YC Chen, M Chertok, G Chiarelli, G Chlachidze, F Chlebana, I Cho, K Cho, D Chokheli, JP Chou, G Choudalakis, SH Chuang, K Chung, WH Chung, YS Chung, M Cilijak

Abstract:

We report the observation and measurement of the mass of the bottom, strange baryon Ξb- through the decay chain Ξb-→J/ψΞ-, where J/ψ→μ+μ-, Ξ-→Λπ-, and Λ→pπ-. A signal is observed whose probability of arising from a background fluctuation is 6.6×10-15, or 7.7 Gaussian standard deviations. The Ξb- mass is measured to be 5792.9±2.5(stat) ±1.7(syst)MeV/c2. © 2007 The American Physical Society.
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EURECA – THE EUROPEAN UNDERGROUND RARE EVENT CALORIMETER ARRAY

World Scientific Publishing (2007) 668-677

Authors:

H KRAUS, M BAUER, I BAVYKINA, A BENOIT, J BLÜMER, A BRONIATOWSKI, V BRUDANIN, G BURGHART, P CAMUS, A CHANTELAUZE, M CHAPELLIER, G CHARDIN, C CIEMNIAK, C COPPI, M DE JÉSUS, A DE LESQUEN, H DESCHAMPS, P DI STEFANO, L DUMOULIN, K EITEL, F VON FEILITZSCH, M FESQUET, J GASCON, G GERBIER, C GOLDBACH, M GROS, D HAUFF, S HENRY, M HORN, J IMBER, S INGLEBY, C ISAILA, J JOCHUM, A JUILLARD, M KIMMERLE, J-C LANFRANCHI, R LEMRANI, A LUBASHEVSKY, M LUCA, M MALEK, S MARNIEROS, R MCGOWAN, V MIKHAILIK, X-F NAVICK, T NIINIKOSKI, G NOLLEZ, E PANTIC, P PARI, L PEREVOSHCHIKOV, F PETRICCA, S PFISTER, W POTZEL, F PRÖBST, F RITTER, K ROTTLER, V SANGLARD, S SCHOLL, F SCHWAMM, W SEIDEL, A SMOLNIKOV, M STERN, M TESHIMA, B TOLHURST, W WESTPHAL, P WIKUS, J WOLF, E YAKUSHEV
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Leading neutron energy and pT distributions in deep inelastic scattering and photoproduction at HERA

Nuclear Physics B 776:1-2 (2007) 1-37

Authors:

S Chekanov, M Derrick, S Magill, S Miglioranzi, B Musgrave, D Nicholass, J Repond, R Yoshida, MCK Mattingly, M Jechow, 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, D Bartsch, I Brock, S Goers, H Hartmann, E Hilger, HP Jakob, M Jüngst, OM Kind, E Paul, R Renner, U Samson, V Schönberg, R Shehzadi, 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, C Blohm, A Bonato, K Borras, N Coppola, A Dossanov, J Fourletova, A Geiser, D Gladkov, P Göttlicher, I Gregor, T Haas, W Hain, C Horn, B Kahle, U Klein

Abstract:

The production of energetic neutrons in ep collisions has been studied with the ZEUS detector at HERA. The neutron energy and pT2 distributions were measured with a forward neutron calorimeter and tracker in a 40   pb-1 sample of inclusive deep inelastic scattering (DIS) data and a 6   pb-1 sample of photoproduction data. The neutron yield in photoproduction is suppressed relative to DIS for the lower neutron energies and the neutrons have a steeper pT2 distribution, consistent with the expectation from absorption models. The distributions are compared to HERA measurements of leading protons. The neutron energy and transverse-momentum distributions in DIS are compared to Monte Carlo simulations and to the predictions of particle exchange models. Models of pion exchange incorporating absorption and additional secondary meson exchanges give a good description of the data. © 2007 Elsevier B.V. All rights reserved.
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Measurement of D Mesons Production in Deep Inelastic Scattering at HERA

Journal of High Energy Physics (2007)

Authors:

JE Ferrando, L. Labarga, M. Zambrana, R. Walsh
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Measurement of D mesons production in deep inelastic scattering at HERA

Journal of High Energy Physics Institute of Physics 2007:7 (2007)

Authors:

Claire Gwenlan, Amanda M Cooper-Sarkar, Robin CE Devenish, Brian Foster, Roman Walczak

Abstract:

Charm production in deep inelastic scattering has been measured with the ZEUS detector at HERA using an integrated luminosity of 82 pb^−1. Charm has been tagged by reconstructing D∗+, D0, D+ and D+s (+ c.c.) charm mesons. The charm hadrons were measured in the kinematic range pT(D∗+, D0, D+) > 3 GeV, pT(D+s) > 2 GeV and |η(D)| < 1.6 for 1.5 < Q2 < 1000 GeV^2 and 0.02 < y < 0.7. The production cross sections were used to extract charm fragmentation ratios and the fraction of c quarks hadronising into a particular charm meson in the kinematic range considered. The cross sections were compared to the predictions of next-to-leading-order QCD, and extrapolated to the full kinematic region in pT (D) and η(D) in order to determine the open-charm contribution, Fc¯ c2 (x, Q^2), to the proton structure function F2.

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