A Search for Leptoquarks at HERA H1 Collaboration

ASearchforLeptoquarksatHERAH1CollaborationAbstractAsearchforleptoquarksatHERAwasperformedinH1using1994e+pdatacor-respondingtoanintegratedluminosityofabout3pb1.Singleleptoquarksweresearchedforindirectpositron-quarkfusionprocessestakingintoaccountpossibledecaysintolepton-quarkpairsofeithertherst,thesecond,orthethirdgener-ation.NosignicantdeviationfromtheStandardModelpredictionsisfoundinthevariousnalstatesstudiedandmassdependentexclusionlimitsarederivedontheYukawacouplingsoftheleptoquarks.Comparedwithearlierresultsfromananalysisofepdata,exclusionlimitsareconsiderablyimprovedforleptoquarkswhichcouldbeproducedviae+-valencequarkfusion.Forleptoquarkswithleptonavourconservingcouplings,massesupto275GeV(dependingontheleptoquarktype)areexcludedforcouplingvalueslargerthanp4em.Forleptoquarkswithleptonavourviolatingcouplings,massesupto225GeVareexcludedforthersttimeinadirectsearchforcouplingswithleptonsofthesecondorthirdgenerationlargerthanp4em.Fourteenpossiblecombinationsofcouplingsarestudiedandstringentexclusionlimitscomparableorbetterthananyexistingdirectorindirectlimitsareobtainedforeachleptoquarktype.S.Aid14,V.Andreev26,B.Andrieu29,R.-D.Appuhn12,M.Arpagaus37,A.Babaev25,J.Bahr36,J.Ban18,Y.Ban28,P.Baranov26,E.Barrelet30,R.Barschke12,W.Bartel12,M.Barth5,U.Bassler30,H.P.Beck38,H.-J.Behrend12,A.Belousov26,Ch.Berger1,G.Bernardi30,R.Bernet37,G.Bertrand-Coremans5,M.Besancon10,R.Beyer12,P.Biddulph23,P.Bispham23,J.C.Bizot28,V.Blobel14,K.Borras9,F.Botterweck5,V.Boudry29,A.Braemer15,W.Braunschweig1,V.Brisson28,D.Bruncko18,C.Brune16,R.Buchholz12,L.Bungener14,J.Burger12,F.W.Busser14,A.Buniatian12;39,S.Burke19,M.J.Burton23,G.Buschhorn27,A.J.Campbell12,T.Carli27,F.Charles12,M.Charlet12,D.Clarke6,A.B.Clegg19,B.Clerbaux5,S.Cocks20,J.G.Contreras9,C.Cormack20,J.A.Coughlan6,A.Courau28,M.-C.Cousinou24,Ch.Coutures10,G.Cozzika10,L.Criegee12,D.G.Cussans6,J.Cvach31,S.Dagoret30,J.B.Dainton20,W.D.Dau17,K.Daum35,M.David10,C.L.Davis19,B.Delcourt28,L.DelBuono30,A.DeRoeck12,E.A.DeWolf5,M.Dirkmann9,P.Dixon19,P.DiNezza33,W.Dlugosz8,C.Dollfus38,J.D.Dowell4,H.B.Dreis2,A.Droutskoi25,J.Duboc30,D.Dullmann14,O.Dunger14,H.Duhm13,J.Ebert35,T.R.Ebert20,G.Eckerlin12,V.Efremenko25,S.Egli38,R.Eichler37,F.Eisele15,E.Eisenhandler21,R.J.Ellison23,E.Elsen12,M.Erdmann15,W.Erdmann37,E.Evrard5,A.B.Fahr14,L.Favart5,A.Fedotov25,D.Feeken14,R.Felst12,J.Feltesse10,J.Ferencei18,F.Ferrarotto33,K.Flamm12,M.Fleischer9,M.Flieser27,G.Flugge2,A.Fomenko26,B.Fominykh25,M.Forbush8,J.Formanek32,J.M.Foster23,G.Franke12,E.Fretwurst13,E.Gabathuler20,K.Gabathuler34,F.Gaede27,J.Garvey4,J.Gayler12,M.Gebauer9,A.Gellrich12,H.Genzel1,R.Gerhards12,A.Glazov36,U.Goerlach12,L.Goerlich7,N.Gogitidze26,M.Goldberg30,D.Goldner9,K.Golec-Biernat7,B.Gonzalez-Pineiro30,I.Gorelov25,C.Grab37,H.Grassler2,R.Grassler2,T.Greenshaw20,R.Griths21,G.Grindhammer27,A.Gruber27,C.Gruber17,J.Haack36,D.Haidt12,L.Hajduk7,O.Hamon30,M.Hampel1,M.Hapke12,W.J.Haynes6,G.Heinzelmann14,R.C.W.Henderson19,H.Henschel36,I.Herynek31,M.F.Hess27,W.Hildesheim12,K.H.Hiller36,C.D.Hilton23,J.Hladky31,K.C.Hoeger23,M.Hoppner9,D.Homann12,T.Holtom20,R.Horisberger34,V.L.Hudgson4,M.Hutte9,H.Hufnagel15,M.Ibbotson23,H.Itterbeck1,M.-A.Jabiol10,A.Jacholkowska28,C.Jacobsson22,M.Jare28,J.Janoth16,T.Jansen12,L.Jonsson22,K.Johannsen14,D.P.Johnson5,L.Johnson19,H.Jung10,P.I.P.Kalmus21,M.Kander12,D.Kant21,R.Kaschowitz2,U.Kathage17,J.Katzy15,H.H.Kaufmann36,S.Kazarian12,I.R.Kenyon4,S.Kermiche24,C.Keuker1,C.Kiesling27,M.Klein36,C.Kleinwort12,G.Knies12,W.Ko8,T.Kohler1,J.H.Kohne27,H.Kolanoski3,F.Kole8,S.D.Kolya23,V.Korbel12,M.Korn9,P.Kostka36,S.K.Kotelnikov26,T.Kramerkamper9,M.W.Krasny7;30,H.Krehbiel12,D.Krucker2,U.Kruger12,U.Kruner-Marquis12,H.Kuster22,M.Kuhlen27,T.Kurca36,J.Kurzhofer9,D.Lacour30,B.Laforge10,F.Lamarche29,R.Lander8,M.P.J.Landon21,W.Lange36,U.Langenegger37,P.Lanius27,J.-F.Laporte10,A.Lebedev26,F.Lehner12,C.Leverenz12,S.Levonian26,Ch.Ley2,G.Lindstrom13,M.Lindstroem22,J.Link8,F.Linsel12,J.Lipinski14,B.List12,G.Lobo28,P.Loch28,H.Lohmander22,J.W.Lomas23,G.C.Lopez13,V.Lubimov25,D.Luke9;12,N.Magnussen35,E.Malinovski26,S.Mani8,R.Maracek18,P.Marage5,J.Marks24,R.Marshall23,J.Martens35,G.Martin14,R.Martin20,H.-U.Martyn1,J.Martyniak7,S.Masson2,T.Mavroidis21,S.J.Maxeld20,S.J.McMahon20,A.Mehta6,K.Meier16,T.Merz36,1A.Meyer12,A.Meyer14,H.Meyer35,J.Meyer12,P.-O.Meyer2,A.Migliori29,S.Mikocki7,D.Milstead20,J.Moeck27,F.Moreau29,J.V.Morris6,E.Mroczko7,D.Muller38,G.Muller12,K.Muller12,P.Murn18,V.Nagovizin25,R.Nahnhauer36,B.Naroska14,Th.Naumann36,P.R.Newman4,D.Newton19,D.Neyret30,H.K.Nguyen30,T.C.Nicholls4,F.Niebergall14,C.Niebuhr12,Ch.Niedzballa1,H.Niggli37,R.Nisius1,G.Nowak7,G.W.Noyes6,M.Nyberg-Werther22,M.Oakden20,H.Oberlack27,U.Obrock9,J.E.Olsson12,D.Ozerov25,P.Palmen2,E.Panaro12,A.Panitch5,C.Pascaud28,G.D.Patel20,H.Pawletta2,E.Peppel36,E.Perez10,J.P.Phillips20,A.Pieuchot24,D.Pitzl37,G.Pope8,S.Prell12,R.Prosi12,K.Rabbertz1,G.Radel12,F.Raupach1,P.Reimer31,S.Reinshagen12,H.Rick9,V.Riech13,J.Riedlberger37,F.Riepenhaus