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Measurement of open beauty production at HERA in the D *μ final state

European Physical Journal C 50:2 (2007) 299-314

Authors:

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

Abstract:

The production of beauty quarks with a D*± and a muon in the final state has been measured with the ZEUS detector at HERA using an integrated luminosity of 114 pb-1. Low transverse-momentum thresholds for the muon and D* meson allow for a measurement of beauty production closer to the production threshold than previous measurements. The beauty signal was extracted using the charge correlations and angular distributions of the muon with respect to the D* meson. Cross sections for photoproduction and deep inelastic scattering are somewhat higher than, but compatible with, next-to-leading-order QCD predictions, and compatible with other measurements. © Springer-Verlag Berlin Heidelberg 2007.
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Photoproduction of events with rapidity gaps between jets at HERA

European Physical Journal C 50:2 (2007) 283-297

Authors:

S Chekanov, M Derrick, S Magill, S Miglioranzi, B Musgrave, D Nicholass, J Repond, R Yoshida, MCK Mattingly, N Pavel, AGY 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, G Aghuzumtsyan, D Bartsch, I Brock, S Goers, H Hartmann, E Hilger, HP Jakob, M Jüngst, OM Kind, E Paul, J Rautenberg, R Renner, U Samson, V Schönberg, M Wang, 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, WATW 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 Bold, I Grabowska-Bold, D Kisielewska, J Lukasik, M Przybycien, L Suszycki, A Kotanski, W Slominski, V Adler, U Behrens, I Bloch, A Bonato, K Borras, N Coppola, J Fourletova, A Geiser, D Gladkov, P Göttlicher, I Gregor, T Haas, W Hain, C Horn, B Kahle, U Kötz, H Kowalski

Abstract:

The photoproduction of dijet events, where the two jets with the highest transverse energy are separated by a large gap in pseudorapidity, have been studied with the ZEUS detector using an integrated luminosity of 39 pb -1. Rapidity-gap events are defined in terms of the energy flow between the jets, such that the total summed transverse energy in this region is less than some value ETCUT. The data show a clear excess over the predictions of standard photoproduction models. This is interpreted as evidence for a strongly interacting exchange of a color-singlet object. Monte Carlo models which include such a color-singlet exchange are able to describe the data. © Springer-Verlag Berlin Heidelberg 2007.
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Measurement of Ks, Lambda and antiLambda production at HERA

European Physical Journal C 51 (2007) 1-23

Authors:

RA Walczak, A. Cottrell, C. Liu, D.H. Saxon
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Measurement of open beauty production at HERA in the D* muon final state

European Physical Journal C C 50 (2007) 299-314

Authors:

B Foster, A. Geiser, L. Bellegamba, I. Bloch
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Modeling of a square pulsed capillary discharge waveguide for interferometry measurements

Physics of Plasmas 14:2 (2007)

Authors:

BHP Broks, W Van Dijk, JJAW Van Der Mullen, AJ Gonsalves, TP Rowlands-Rees, SM Hooker

Abstract:

Slow pulsed capillary discharges in round capillaries are currently under investigation for use as plasma channel laser waveguides in laser-wakefield acceleration, x-ray lasers, and higher-harmonic generation. In this study, a capillary discharge with a square cross section is presented. The electron density, which determines the laser guiding properties, can be measured by means of transverse interferometry in this device. Using a numerical model of the plasma and the capillary wall, an analysis of the discharge is made. The results predict that the square channel is capable of guiding circular laser pulses. The guiding properties are quite similar to those of a round channel with nearly the same diameter as the channel width. This suggests the results obtained by measuring the square capillary discharge are applicable for round channels as well. It was found that the wall heating was inhomogeneous, which makes the wall more susceptible to ablation. The heating of the wall changes the transverse optical pathlength in the interferometry experiments. © 2007 American Institute of Physics.
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