Measurement of Beauty Photoproduction near Threshold using Di-electron Events with the H 1 Detector at HERA H 1 Collaboration

The cross section for ep → e bb̄X in photoproduction is measured with the H1 detector at theep-collider HERA. The decay channel bb̄ → eeX ′ is selected by identifying the semielectronic decays of the b-quarks. The total production cross section is measured in the kinematic range given by the photon virtuality Q2 ≤ 1 GeV, the inelasticity0.05 ≤ y ≤ 0.65 and the pseudorapidity of the b-quarks|η(b)|, |η(b̄)| ≤ 2. The differential production cross section is measured as a function of the average transverse momentu m of the beauty quarks〈PT (b)〉 down to the threshold. The results are compared to next-to-leading-order QCD predictions. Submitted toEur. Phys. J.C F.D. Aaron, C. Alexa, V. Andreev, S. Backovic, A. Baghdasaryan , S. Baghdasaryan , E. Barrelet , W. Bartel, K. Begzsuren , A. Belousov, P. Belov, J.C. Bizot , V. Boudry, I. Bozovic-Jelisavcic , J. Bracinik, G. Brandt , M. Brinkmann, V. Brisson, D. Britzger, D. Bruncko, A. Bunyatyan, A. Bylinkin, L. Bystritskaya, A.J. Campbell , K.B. Cantun Avila, F. Ceccopieri , K. Cerny, V. Cerny, V. Chekelian, J.G. Contreras , J.A. Coughlan, J. Cvach, J.B. Dainton, K. Daum, B. Delcourt , J. Delvax, E.A. De Wolf, C. Diaconu, M. Dobre, V. Dodonov, A. Dossanov , A. Dubak, G. Eckerlin, S. Egli, A. Eliseev, E. Elsen, L. Favart, A. Fedotov, R. Felst , J. Feltesse , J. Ferencei , D.-J. Fischer , M. Fleischer , A. Fomenko, E. Gabathuler , J. Gayler , S. Ghazaryan , A. Glazov, L. Goerlich, N. Gogitidze, M. Gouzevitch, C. Grab, A. Grebenyuk, T. Greenshaw, G. Grindhammer , S. Habib, D. Haidt, R.C.W. Henderson , E. Hennekemper , H. Henschel , M. Herbst , G. Herrera, M. Hildebrandt , K.H. Hiller, D. Hoffmann, R. Horisberger , T. Hreus, F. Huber, M. Jacquet , X. Janssen , L. Jönsson, A.W. Jung, H. Jung, M. Kapichine, I.R. Kenyon, C. Kiesling, M. Klein, C. Kleinwort, R. Kogler, P. Kostka, M. Krämer, J. Kretzschmar , K. Krüger, M.P.J. Landon , W. Lange, G. Lǎstovǐcka-Medin, P. Laycock, A. Lebedev, V. Lendermann, S. Levonian, K. Lipka, B. List, J. List, B. Lobodzinski , R. Lopez-Fernandez , V. Lubimov, E. Malinovski, H.-U. Martyn, S.J. Maxfield, A. Mehta, A.B. Meyer, H. Meyer, J. Meyer, S. Mikocki, I. Milcewicz-Mika, F. Moreau, A. Morozov, J.V. Morris, K. Müller, Th. Naumann , P.R. Newman , C. Niebuhr , D. Nikitin, G. Nowak, K. Nowak, B. Olivier, J.E. Olsson , D. Ozerov, P. Pahl , V. Palichik, M. Pandurovic, C. Pascaud , G.D. Patel , E. Perez, A. Petrukhin, I. Picuric, H. Pirumov, D. Pitzl, R. Plǎcakyṫe, B. Pokorny, R. Polifka, B. Povh, V. Radescu , N. Raicevic, T. Ravdandorj , P. Reimer , E. Rizvi, P. Robmann , R. Roosen , A. Rostovtsev , M. Rotaru, J.E. Ruiz Tabasco , S. Rusakov , D. Šálek, D.P.C. Sankey , M. Sauter , E. Sauvan, S. Schmitt , L. Schoeffel , A. Scḧoning, H.-C. Schultz-Coulon , F. Sefkow, L.N. Shtarkov, S. Shushkevich , T. Sloan, Y. Soloviev, P. Sopicki , D. South, V. Spaskov, A. Specka, Z. Staykova, M. Steder , B. Stella, G. Stoicea, U. Straumann , T. Sykora, P.D. Thompson , T.H. Tran, D. Traynor, P. Trüol, I. Tsakov, B. Tseepeldorj , J. Turnau, A. Valkárov́a, C. Vallée, P. Van Mechelen , Y. Vazdik, D. Wegener , E. Wünsch, J.Žáček, J. Źalěsák, Z. Zhang, A. Zhokin, R. Žlebč́ık, H. Zohrabyan, and F. Zomer 27 1 I. Physikalisches Institut der RWTH, Aachen, Germany 2 Vinca Institute of Nuclear Sciences, University of Belgrad e, 1100 Belgrade, Serbia 3 School of Physics and Astronomy, University of Birmingham, Birmingham, UK 4 Inter-University Institute for High Energies ULB-VUB, Bru ssels and Universiteit Antwerpen, Antwerpen, Belgium 5 National Institute for Physics and Nuclear Engineering (NI P E) , Bucharest, Romania k 6 STFC, Rutherford Appleton Laboratory, Didcot, Oxfordshire , UK 7 Institute for Nuclear Physics, Cracow, Poland d 8 Institut für Physik, TU Dortmund, Dortmund, Germany a 9 Joint Institute for Nuclear Research, Dubna, Russia 10 CEA, DSM/Irfu, CE-Saclay, Gif-sur-Yvette, France 11 DESY, Hamburg, Germany 1 12 Institut für Experimentalphysik, Universit ät Hamburg, Hamburg, Germany a 13 Max-Planck-Institut f̈ ur Kernphysik, Heidelberg, Germany 14 Physikalisches Institut, Universit ät Heidelberg, Heidelberg, Germany a 15 Kirchhoff-Institut f̈ur Physik, Universiẗ at Heidelberg, Heidelberg, Germany a 16 Institute of Experimental Physics, Slovak Academy of Scien ces, Kǒsice, Slovak Republic e 17 Department of Physics, University of Lancaster, Lancaster , UK 18 Department of Physics, University of Liverpool, Liverpool , UK 19 School of Physics and Astronomy, Queen Mary, University of L ondon, London, UK 20 Physics Department, University of Lund, Lund, Sweden f 21 CPPM, Aix-Marseille Univ, CNRS/IN2P3, 13288 Marseille, Fran ce 22 Departamento de Fisica Aplicada, CINVESTAV, M érida, Yucat́ an, México 23 Departamento de Fisica, CINVESTAV IPN, M éxico City, Ḿexico 24 Institute for Theoretical and Experimental Physics, Mosco w, Russia 25 Lebedev Physical Institute, Moscow, Russia 26 Max-Planck-Institut f̈ ur Physik, M̈unchen, Germany 27 LAL, Universit́e Paris-Sud, CNRS/IN2P3, Orsay, France 28 LLR, Ecole Polytechnique, CNRS/IN2P3, Palaiseau, France 29 LPNHE, Universit́ e Pierre et Marie Curie Paris 6, Universit é Denis Diderot Paris 7, CNRS/IN2P3, Paris, France 30 Faculty of Science, University of Montenegro, Podgorica, M ontenegro 31 Institute of Physics, Academy of Sciences of the Czech Republ ic, Praha, Czech Republic g 32 Faculty of Mathematics and Physics, Charles University, Pra ha, Czech Republic g 33 Dipartimento di Fisica Universit̀ a di Roma Tre and INFN Roma 3, Roma, Italy 34 Institute for Nuclear Research and Nuclear Energy, Sofia, Bu lgaria 35 Institute of Physics and Technology of the Mongolian Academ y of Sciences, Ulaanbaatar, Mongolia 36 Paul Scherrer Institut, Villigen, Switzerland 37 Fachbereich C, Universit ät Wuppertal, Wuppertal, Germany 38 Yerevan Physics Institute, Yerevan, Armenia 39 DESY, Zeuthen, Germany 40 Institut für Teilchenphysik, ETH, Z̈ urich, Switzerland 41 Physik-Institut der Universit ät Zürich, Zürich, Switzerland 42 Also at Rechenzentrum, Universit ät Wuppertal, Wuppertal, Germany 43 Also at IPNL, Universit́ e Claude Bernard Lyon 1, CNRS/IN2P3, Villeurbanne, France 44 Also at CERN, Geneva, Switzerland 45 Also at Faculty of Physics, University of Bucharest, Buchar est, Romania 46 Also at Ulaanbaatar University, Ulaanbaatar, Mongolia 47 Supported by the Initiative and Networking Fund of the Helmho ltz Association (HGF) under the contract VH-NG-401. 48 Absent on leave from NIPNE-HH, Bucharest, Romania 49 Also at Department of Physics, University of Toronto, Toron to, Ontario, Canada M5S 1A7 50 Also at LAPP, Universit́ e de Savoie, CNRS/IN2P3, Annecy-le-Vieux, France 51 Now at Fermi National Accelerator Laboratory, Batavia, Ill inois 60510, USA a Supported by the Bundesministerium f ür Bildung und Forschung, FRG, under contract numbers 05H09GUF, 05H09VHC, 05H09VHF, 05H16PEA 2 b Supported by the UK Science and Technology Facilities Counci l, and formerly by the UK Particle Physics and Astronomy Research Council c Supported by FNRS-FWO-Vlaanderen, IISN-IIKW and IWT and by Interuniversity Attraction Poles Programme, Belgian Science Policy d Partially Supported by Polish Ministry of Science and Highe r Education, grant DPN/N168/DESY/2009 e Supported by VEGA SR grant no. 2/7062/ 27 f Supported by the Swedish Natural Science Research Council g Supported by the Ministry of Education of the Czech Republic u nder the projects LC527, INGO-LA09042 and MSM0021620859 h Supported by the Swiss National Science Foundation i Supported by CONACYT, M éxico, grant 48778-F j Russian Foundation for Basic Research (RFBR), grant no 1329 .2008.2 and Rosatom k Supported by the Romanian National Authority for Scientific Research under the contract PN 09370101 l Partially Supported by Ministry of Science of Montenegro, n o. 05-1/3-3352