Photoproduction of [formula omitted] mesons at HERA

T Ahmed ,M Vecko,H Spitzer,J Haack,W Struczinski,H Shooshtari,J Feltesse,C Vallée,J Stiewe,P Steffen,J Bán,W Braunschweig,P Kostka,J Turnau,M Savitsky,J Heatherington,K Gamerdinger,H Genzel,B Stella,M Steenbock,E Peppel,A De Roeck,E Panaro,B Delcourt,T Greenshaw,R Buchholz,G Grindhammer,A Gellrich,L Hajduk,K Wacker,M Forbush,U Krüner-Marquis,D Feeken,G Franke,R Grässler,D Neyret,F Ferrarotto,T Kurlen,P Ribarics,G Cozzika,Y Soloviev,R Prosi,J Žáček,W Hildesheim,H Küster,V Borrdry,Ph Huet,A Courau,P Di Nezza,H Ehrlichmann,Y Vazdik,N Magnussen,G Buschhorn,A Lebedev,D Newton,A Valkárová,V Tchernyshov,U Obrock,J Garvey,D Kant,K Johannsen,M Höppner,A Walther,H Itterbeck,K Gabathuler,F Sefkow,D Goldner,M Rietz,S Masson,K Müller,A Braemer,L Büngener,E Eisenhandler,M Ibbotson,K Stephens,I Tichomirov,B Fominykh,J Ferencei,J Riedlberger,J Marks,W.D Dau,J Strachota,E Malinovski,S Prell,W Zimmermann,K Daum,U Siewert,J Cvach,F Linsel,R Robmann,C Pascaud,N Gogitidze,A Buniatian,C Keuker,P Verrecchia,R Kaschowitz,P Biddulph,L Criegee,J Formánek,G Rädel,J.C Bizot,Ch Berger,F Botterweck,I Herynek,M Wagener,D Haidt,J Janoth,K Rüter,S Schiek,V Blodel,R Eichler,F Niebergall,S Egli,H Bergstein,P Uelkes,V Efremenko,R Steinberg,C Jacobsson,V Schröder,G Knies,E Evrard,M Nyberg-Werther,M Flieser,O Dünger,T Mavroidis,D Mercer,R Roosen,P Hill,M Winde,J Hladký,M Arpagaus,G Weber,F Moreau,U Seehausen,U Krüger,D Düllmann,G Lindström,H Krehbiel,S Reinshagen,M Fleischer,P Lanius,F Eisele,E Deffur,C Kiesling,M Zimmer,A Rostovtsev,A Schwind,F Kole,M Gebauer,W Bartel,A Usik,H Lohmander,V Brisson,G Siegmon,H Grässler,Ch Ley,R Gerhards,A Lindner,C Dollfus,A Wegner,U Kathage,B Naroska,W.J Haynes,J Stier,E Schuhmann,C Niebuhr,F Rouse,J Martyniak,I Sheviakov,C.D Hilton,C Leverenz,R Felst,P Truöl,P Kasselmann,B Schwab,J Gayler,E Barrelet,D Lüke,J Kurzhöfer,S Mani,G Bertrand-Coremans,R Maraček,R Starosta,A Semenov,G Pope,S Levonian,L Del Buono,L Goerlich,P Goritchev,J Duboc,D Zarbock,V Korbel,D Wegener,M Hapke,F Charles,W Von Schlippe,K Flamm,K Rosenbauer,M Korn,R Nahnhauer,G Heinzelmann,O Hamon,R Marshall,U Straumann,S Kermiche,R Herma,S Dagoret,J Tutas,J Ebert,U Bassler,S Eichenberger,A Panitch,S Mikocki,F Lamarche,G Villet,K Rybicki,N Wulff,P Van Mechelen,S Willard,E Gabathuler,H Hufnagel,H Henschel,N Sahlmann,V Riech ,C Schmidt ,P Schleper ,H U Martyn ,R Horisberger ,Y Sirois ,A Belousov ,P Loch ,E Sánchez ,A Fomenko ,G W Noyes ,H P Beck ,D P C Sankey ,M Colombo ,L Johnson ,J G Contreras ,A Schöning ,J V Morris ,R Ryłko ,J Bürger ,M Weber ,G Schmidt ,G Nowak ,J B Dainton ,Thomas L C Jansen ,L Favart ,A Campbell ,I R Kenyon ,D Krücker ,A Mehta ,H Kolanoski ,J Lipiński ,J Meyer ,P Schacht ,T Naumann ,D Cussans ,I Gorelov ,A Babaev ,T Kurča ,M Klein ,V Shekelyan ,Ch Thiebaux ,K Borras ,M A Jabiol ,D Pitzl ,A Gruber ,S V Rusakov ,H Meyer ,U Goerlach ,H H Kaufmann ,G Bernardi ,R Beyer ,G Müller ,R Lander ,E M Hanlon ,B List ,J Baehr ,K C Hoeger ,H.h Duhm ,S J Mcmahon ,Ch Pichler ,Thomas Köhler ,M Seidel ,Shahé S Kazarian ,M Heß ,H P Wellisch ,C Royon ,W Erdmann ,P Smirnov ,C Kleinwort ,J P Sutton ,D.p Johnson ,J E Olsson ,J P Kubenka ,A Jachołkowska ,J M Foster ,R C W Henderson ,E A De Wolf ,D Milstead ,A Fedotov ,M W Krasny ,R Martin ,G G Winter ,R J Ellison ,L.r West ,P Marage ,F.w Brasse ,D Schmidt ,Aurélie Wagener ,S Rieß ,G Flügge ,S Tapprogge ,C Coutures ,H Jung ,H E Roloff ,J A Coughlan ,L N Shtarkov ,C Grubber ,H K Nguyen ,M Barth ,W Ko ,Z Zhang ,P I P Kalmus ,S.k Kotelnikov ,E Pérez ,G D Patel ,M Jaffré ,T Merz ,A M Goodall ,I W Walker ,Patrick Van Esch ,F.w Büsser ,Š Valkár ,T R Ebert ,S D Kolya ,S J Maxfield ,F Zomer ,H J Behrend ,U Stößlein ,T Carli ,M David ,D Clarke ,M Erdmann ,W Lange ,V A Andreev ,A.e Wright ,H Oberlack ,П Мурін ,Jack Smith ,K H Hiller ,J P Phillips ,A.b Clegg ,Bernard Andrieu ,M Goldberg ,J F Laporte ,B González-Pineiro ,I O Skillicorn ,G Eckerlin ,D Bruncko ,G Thompson ,S Aïd ,M Besançon ,R Nisius ,J Martens ,F Raupach ,A Vartapetian ,T P Yiou ,L Jönsson ,C R Brune ,S Bürke ,K Meier ,G C Lopez ,P Baranov ,D Lacour ,V Hedberg ,S Robertson ,Б И Кузник ,C Grab ,P R Newman ,M P J Landon ,Matías Rolf Hampel ,E Fretwurst ,R Bernet ,Raivo Sell ,R D Appuhn ,H B Dreis ,P Reimer ,Richard E Taylor ,E Wünsch ,Chris Meyer ,J D Dowell ,E Elsen ,M Danilov ,Κ Zuber

doi:10.1016/0370-2693(94)90806-0

Abstract

We present a study of J ψ meson production in collisions of 26.7 GeV electrons with 820 GeV protons, performed with the H1-detector at the HERA collider at DESY. The J ψ mesons are detected via their leptonic decays both to electrons and muons. Requiring exactly two particles in the detector, a cross section of σ(ep → J ψ X) = (8.8±2.0±2.2) nb is determined for 30 GeV ≤ W γp ≤ 180 GeV and Q 2 ≲ 4 GeV 2. Using the flux of quasi-real photons with Q 2 ≲ 4 GeV 2, a total production cross section of σ( γp → J/ ψX) = (56±13±14) nb is derived at an average W γp =90 GeV. The distribution of the squared momentum transfer t from the proton to the J ψ can be fitted using an exponential exp(− b∥ t∥) below a ∥ t∥ of 0.75 GeV 2 yielding a slope parameter of b = (4.7±1.9) GeV −2.

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