Multi-lepton production at high transverse momenta in ep collisions at HERA
F. D. AaronNational Institute for Physics and Nuclear Engineering (NIPNE), Bucharest, RomaniaC. AlexaNational Institute for Physics and Nuclear Engineering (NIPNE), Bucharest, RomaniaVladimir AndreevLebedev Physical Institute, Moscow, Russia 16B. AntunovićS. AplinA. AsmoneA. AstvatsatourovInter-University Institute for High Energies ULB-VUB, Brussels, Universiteit Antwerpen, Antwerpen, Belgium 14Alessandro BacchettaS. BackovićFaculty of Science, University of Montenegro, Podgorica, Montenegro 16A. BaghdasaryanYerevan Physics Institute, Yerevan, ArmeniaP. BaranovLebedev Physical Institute, Moscow, Russia 16E. BarreletSorbonne UniversitéW. BartelM. BeckinghamK. BegzsurenInstitute of Physics and Technology of the Mongolian Academy of Sciences, Ulaanbaatar, MongoliaO. BehnkePhysikalisches Institut, Universität Heidelberg, Heidelberg, Germany 12A. BelousovLebedev Physical Institute, Moscow, Russia 16N. BergerInstitut für Teilchenphysik, ETH, Zürich, Switzerland 20J.C. BizotInstitut National de Physique Nucléaire et de Physique des ParticulesM.-O. BoenigInstitut für Physik, TU Dortmund, Dortmund, Germany 12V. BoudryLLR, Ecole Polytechnique, IN2P3-CNRS, Palaiseau, FranceI. Božović-Jelisavc̆ićVinca Institute of Nuclear Sciences, Belgrade, SerbiaJ. BraciníkInstitut National de Physique Nucléaire et de Physique des ParticulesG. BrandtMartin BrinkmannV. BrissonInstitut National de Physique Nucléaire et de Physique des ParticulesD. BrunckoInstitute of Experimental Physics of the Slovak Academy of SciencesA. BunyatyanMax-Planck-Institut für Kernphysik, Heidelberg, GermanyG. BuschhornMax-Planck-Institut für Physik, München, GermanyL. BystritskayaInstitute for Theoretical and Experimental Physics, Moscow, RussiaAlan CampbellK. B. Cantun AvilaCentro de Investigación y de Estudios Avanzados del Instituto Politécnico NacionalF. Cassol-BrunnerNational Institute for Physics and Nuclear Engineering (NIPNE), Bucharest, RomaniaK. ČernýFaculty of Mathematics and Physics, Charles University, Praha, Czech Republic 19V. ČernýInstitute of Experimental Physics of the Slovak Academy of SciencesV. ChekelianMax-Planck-Institut für Physik, München, GermanyA. CholewaJ.G. ContrerasDepartamento de Fisica Aplicada, CINVESTAV, Mérida, Yucatán, Mexico 21J. A. CoughlanRutherford Appleton Laboratory, Chilton, Didcot, UK 13G. CozzikaCEA Paris-SaclayJ. CvachCzech Academy of SciencesJ.B. DaintonDepartment of Physics, University of Liverpool, Liverpool, UK 13K. DaumFachbereich C, Universität Wuppertal, Wuppertal, GermanyMichal DeákY. de BoerDESY, Hamburg, GermanyB. DelcourtInstitut National de Physique Nucléaire et de Physique des ParticulesM. Del DeganInstitut für Teilchenphysik, ETH, Zürich, Switzerland 20J. DelvaxInteruniversity Institute for High EnergiesA. De RoeckE. A. De WolfInter-University Institute for High Energies ULB-VUB, Brussels, Universiteit Antwerpen, Antwerpen, Belgium 14C. DiaconuCPPM, CNRS/IN2P3 – Univ. Mediterranee, Marseille, FranceV. DodonovMax-Planck-Institut für Kernphysik, Heidelberg, GermanyA. DossanovMax-Planck-Institut für Physik, München, GermanyA. DubakFaculty of Science, University of Montenegro, Podgorica, Montenegro 16G. EckerlinV. EfremenkoInstitute for Theoretical and Experimental Physics, Moscow, RussiaS. EgliPaul Scherrer Institut, Villigen, SwitzerlandA. EliseevLebedev Physical Institute, Moscow, Russia 16E. ElsenS. EssenovInstitute for Theoretical and Experimental Physics, Moscow, RussiaA. FalkiewiczInstitute for Nuclear Physics, Cracow, Poland 15Peter FaulknerSchool of Physics and Astronomy, University of Birmingham, Birmingham, UK 13L. FavartInter-University Institute for High Energies ULB-VUB, Brussels, Universiteit Antwerpen, Antwerpen, Belgium 14A. FedotovInstitute for Theoretical and Experimental Physics, Moscow, RussiaR. FelstJ. FeltesseCEA, DSM/DAPNIA, CE-Saclay, Gif-sur-Yvette, FranceJ. FerenceiInstitute of Experimental Physics of the Slovak Academy of SciencesM. FleischerA. FomenkoLebedev Physical Institute, Moscow, Russia 16E. GabathulerDepartment of Physics, University of Liverpool, Liverpool, UK 13J. GaylerDESY, Hamburg, GermanyS. GhazaryanYerevan Physics Institute, Yerevan, ArmeniaA. GlazovI. GlushkovDESY, Zeuthen, GermanyL. GoerlichInstitute for Nuclear Physics, Cracow, Poland 15M. GoettlichInstitut für Experimentalphysik, Universität Hamburg, Hamburg, Germany 12N. GogitidzeLebedev Physical Institute, Moscow, Russia 16M. GouzevitchLLR, Ecole Polytechnique, IN2P3-CNRS, Palaiseau, FranceC. GrabInstitut für Teilchenphysik, ETH, Zürich, Switzerland 20T. GreenshawUniversity of LiverpoolB.R. GrellG. GrindhammerMax-Planck-Institut für Physik, München, GermanyS. HabibInstitut für Experimentalphysik, Universität Hamburg, Hamburg, Germany 12D. HaidtDESY, Hamburg, GermanyM. HanssonPhysics Department, University of Lund, Lund, Sweden 18C. HelebrantDESY, Hamburg, GermanyR. C. W. HendersonDepartment of Physics, University of Lancaster, Lancaster, UK 13E. HennekemperKirchhoff-Institut für Physik, Universität Heidelberg, Heidelberg, Germany 12H. HenschelDESY, Zeuthen, GermanyG. HerreraDepartamento de Fisica, CINVESTAV, Mexico 21M. HildebrandtPaul Scherrer Institut, Villigen, SwitzerlandK. H. HillerDESY, Zeuthen, GermanyD. HoffmannYerevan Physics Institute, Yerevan, ArmeniaR. HorisbergerPaul Scherrer Institut, Villigen, SwitzerlandA. HovhannisyanYerevan Physics Institute, Yerevan, ArmeniaT. HreusInteruniversity Institute for High EnergiesM. JacquetLAL, Univ Paris-Sud, CNRS/IN2P3, Orsay, FranceM.E. JanssenX. JanssenNational Institute for Physics and Nuclear Engineering (NIPNE), Bucharest, RomaniaV. JemanovInstitut für Experimentalphysik, Universität Hamburg, Hamburg, Germany 12
2008en
ABI
Аннотация
Processes leading to a final state with at least two high transverse momentum leptons (electrons or muons) are studied using the full e ± p data sample collected by the H1 experiment at HERA. The data correspond to an integrated luminosity of 463 pb −1 . Di-lepton and tri-lepton event classes are investigated. Cross sections of the production of e + e − and μ + μ − pairs are derived in a restricted phase space dominated by photon–photon collisions. In general, good agreement is found with Standard Model predictions. Events are observed with a total scalar sum of lepton transverse momenta above 100 GeV where the Standard Model expectation is low. In this region, combining di-lepton and tri-lepton classes, five events are observed in e + p collisions, compared to a Standard Model expectation of 0.96 ± 0.12 , while no such event is observed in e − p data for 0.64 ± 0.09 expected.
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