Search for odderon-induced contributions to exclusive π0 photoproduction at HERA
C. AdloffFachbereich Physik, Bergische Universität Gesamthochschule Wuppertal, Wuppertal, GermanyVladimir AndreevLebedev Physical Institute, Moscow, Russia 12B. AndrieuLPNHE, Ecole Polytechnique, IN2P3-CNRS, Palaiseau, FranceT. AnthonisInter-University Institute for High Energies ULB-VUB, Brussels; Universiteit Antwerpen (UIA), Antwerpen; BelgiumV. ArkadovDESY, Zeuthen, GermanyA. AstvatsatourovDESY, Zeuthen, GermanyA. BabaevInstitute for Theoretical and Experimental Physics, Moscow, Russia 18J. BährDESY, Zeuthen, GermanyP. BaranovLebedev Physical Institute, Moscow, Russia 12E. BarreletLaboratoire de Physique Nucléaire et de Hautes ÉnergiesW. BartelJ. BeckerPhysik-Institut der Universität Zürich, Zürich, Switzerland 16A. BeglarianYerevan Physics Institute, Yerevan, ArmeniaO. BehnkePhysikalisches Institut, Universität Heidelberg, Heidelberg, Germany 8C. BeierKirchhoff-Institut für Physik, Universität Heidelberg, Heidelberg, Germany 8A. BelousovLebedev Physical Institute, Moscow, Russia 12Ch. BergerI. Physikalisches Institut der RWTH, Aachen, Germany 8T. BerndtKirchhoff-Institut für Physik, Universität Heidelberg, Heidelberg, Germany 8J.C. BizotUniversité Paris CitéJ. BöhmeV. BoudryLPNHE, Ecole Polytechnique, IN2P3-CNRS, Palaiseau, FranceW. BraunschweigI. Physikalisches Institut der RWTH, Aachen, Germany 8V. BrissonUniversité Paris CitéH.-B. BrökerIII. Physikalisches Institut der RWTH, Aachen, Germany 8Dunstan BrownW. BrücknerMax-Planck-Institut für Kernphysik, Heidelberg, GermanyD. BrunckoInstitute of Experimental Physics, Slovak Academy of Sciences, Košice, Slovak Republic e,J. BürgerF.W. BüsserInstitut für Experimentalphysik, Universität Hamburg, Hamburg, Germany 8A. BunyatyanMax-Planck-Institut für Kernphysik, Heidelberg, GermanyA. BurrageDepartment of Physics, University of Liverpool, Liverpool, UK 9G. BuschhornMax-Planck-Institut für Physik, München, GermanyL. BystritskayaInstitute for Theoretical and Experimental Physics, Moscow, Russia 18A. CampbellJun CaoInstitut National de Physique Nucléaire et de Physique des ParticulesS. CaronI. Physikalisches Institut der RWTH, Aachen, Germany 8F. Cassol-BrunnerFachbereich Physik, Bergische Universität Gesamthochschule Wuppertal, Wuppertal, GermanyD. ClarkeRutherford Appleton Laboratory, Chilton, Didcot, UK 9C. CollardInstitut National de Physique Nucléaire et de Physique des ParticulesJ.G. ContrerasAlso at Dept. Fis. Ap. CINVESTAV, Mérida, Yucatán, MéxicoY.R. CoppensSchool of Physics and Space Research, University of Birmingham, Birmingham, UKJ. A. CoughlanRutherford Appleton Laboratory, Chilton, Didcot, UK 9M.-C. CousinouCPPM, CNRS/IN2P3, Université Mediterranee, Marseille, FranceB. E. CoxPhysics Department, University of Manchester, Manchester, UK 9G. CozzikaCEA Paris-SaclayJ. CvachInstitute of Physics, Academy of Sciences of the Czech Republic, Praha, Czech Republic 12 15J.B. DaintonDepartment of Physics, University of Liverpool, Liverpool, UK 9W.D. DauInstitut für Experimentelle und Angewandte Physik, Universität Kiel, Kiel, GermanyK. DaumFachbereich Physik, Bergische Universität Gesamthochschule Wuppertal, Wuppertal, GermanyMarcus DavidssonPhysics Department, University of Lund, Lund, Sweden 14B. DelcourtInstitut National de Physique Nucléaire et de Physique des ParticulesNicolas DelerueCPPM, CNRS/IN2P3 -Univ Mediterranee, Marseille -FranceR. DemirchyanYerevan Physics Institute, Yerevan, ArmeniaA. De RoeckDESY, Hamburg, GermanyE.A. De WolfInter-University Institute for High Energies ULB-VUB, Brussels; Universiteit Antwerpen (UIA), Antwerpen, Belgium 10C. DiaconuUniversité Paris CitéJ. DingfelderPhysikalisches Institut, Universität Heidelberg, Heidelberg, Germany 8P. DixonQueen Mary and Westfield College, London, UK 9V. DodonovMax-Planck-Institut für Kernphysik, Heidelberg, GermanyJ.D. DowellSchool of Physics and Space Research, University of Birmingham, Birmingham, UK 9A. DroutskoiInstitute for Theoretical and Experimental Physics, Moscow, Russia 18A. DubakMax-Planck-Institut für Physik, München, GermanyC. DuprelLAL, Université de Paris-Sud, IN2P3-CNRS, Orsay, FranceG. EckerlinV. EfremenkoInstitute for Theoretical and Experimental Physics, Moscow, Russia 18S. EgliPaul Scherrer Institut, Villigen, SwitzerlandR. EichlerInstitut für Teilchenphysik, ETH, Zürich, Switzerland 16F. EiseleFachbereich Physik, Bergische Universität Gesamthochschule Wuppertal, Wuppertal, GermanyE. EisenhandlerQueen Mary and Westfield College, London, UK 9M. EllerbrockPhysikalisches Institut, Universität Heidelberg, Heidelberg, Germany 8E. ElsenM. ErdmannPeter FaulknerSchool of Physics and Space Research, University of Birmingham, Birmingham, UKL. FavartInter-University Institute for High Energies ULB-VUB, Brussels; Universiteit Antwerpen (UIA), Antwerpen, Belgium 10A. FedotovInstitute for Theoretical and Experimental Physics, Moscow, Russia 18R. FelstJ. FerenceiS. FerronLPNHE, Ecole Polytechnique, IN2P3-CNRS, Palaiseau, FranceM. FleischerY.H. FlemingSchool of Physics and Space Research, University of Birmingham, Birmingham, UKG. FlüggeIII. Physikalisches Institut der RWTH, Aachen, Germany 8A. FomenkoLebedev Physical Institute, Moscow, Russia 12I. ForestiUniversité Paris CitéJ. FormánekFaculty of Mathematics and Physics, Charles University, Praha, Czech Republic 12 15G. FrankeE. GabathulerDepartment of Physics, University of Liverpool, Liverpool, UK 9K. GabathulerPaul Scherrer Institut, Villigen, SwitzerlandJ. GarveySchool of Physics and Space Research, University of Birmingham, Birmingham, UK 9J. GassnerPaul Scherrer Institut, Villigen, SwitzerlandJ. GaylerR. GerhardsC. GerlichUniversité Paris CitéS. GhazaryanInter-University Institute for High Energies ULB-VUB, Brussels; Universiteit Antwerpen (UIA), Antwerpen; BelgiumL. GoerlichInstitute for Nuclear Physics, Cracow, Poland 11N. GogitidzeLebedev Physical Institute, Moscow, Russia 12T. GollingInstitut National de Physique Nucléaire et de Physique des ParticulesC. GrabInstitut für Teilchenphysik, ETH, Zürich, Switzerland 16Varlen GrabskiYerevan Physics Institute, Yerevan, Armenia
2002en
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Annotatsiya
A search for contributions to the reaction ep→eπ 0 N ∗ from photon–odderon fusion in the photoproduction regime at HERA is reported, at an average photon–proton centre-of-mass energy 〈 W 〉=215 GeV. The measurement proceeds via detection of the π 0 decay photons, a leading neutron from the N ∗ decay, and the scattered electron. No π 0 signal is observed and an upper limit on the cross section for the photon–odderon fusion process of σ(γp→π 0 N ∗ )<49 nb at the 95% confidence level is derived, integrated over the experimentally accessible range of the squared four-momentum transfer at the nucleon vertex 0.02<| t |<0.3 GeV 2 . This excludes a recent prediction from a calculation based on a non-perturbative QCD model of a photon–odderon fusion cross section above 200 nb.
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