A study of muon pair production and evidence for tau pair production in photon-photon collisions at LEP

R Akers ,D E Plane,A Luig,J Goldberg,G A Beck,J P Pansart,H Ihssen,F C Grant,C J Oram,C K Hargrove,M Sproston,P Berlich,A M Smith,R Yaari,M J Losty,W Gorn,A Jawahery,A Yeaman,H Lafoux,R Humbert,B Fabbro,R Mir,S Rossberg,C Wahl,C Y Chang,A Dieckmann,K J Anderson,G N Patrick,P S Wells,M Tecchio,D R Ward,J G Layter,J C Hill,M Fierro,S Orito,K W Bell,I J Bloodworth,R Kowalewski,M H Lehto,D Menszner,A Michelini,M W Redmond,G J Vandalen,M Coupland,R G Kellogg,T W Pritchard,J C Clayton,C Markus,N K Watson,P Mättig,J Banks,M S Dixit,T Hilse,M A Thomson,T Kobayashi,S A Robins,M Settles,M Hauschild,I Cohen,A D Schaile,M A Whalley,J E Pilcher,D L Rees,M J Oreglia,A Astbury,W G Scott,B C Shen,K Runge,F Scharf,T Tsukamoto,M Rosvick,N Paz-Jaoshvili,P Scharff-Hansen,F S Merritt,C P Ward,J E Conboy,G P Siroli,H O Ogren,D Hochman,W R Gibson,P A Elcombe,B Boden,P Weber,R J Hemingway,F K Loebinger,C Beeston,B Lorazo,G Giacomelli,G T Zorn,B W Kennedy,B Poli,M Yurko,C Moisan,R K Carnegie,A Gaidot,P M Hattersley,C M Hawkes,D M Gingrich,P Routenburg,I P Duerdoth,T Kawamoto,D A Hinshaw,A Beck,P Pfister,E Lefebvre,H M Bosch,U Maur,J R Mcnutt,P Paschievici,D Pitman,M Boutemeur,C Burgard,P Poffenberger,D R Rust,B Panzer-Steindel,R E Hughes-Jones,G D Lafferty,E Heflin,P Bock,P Bentkowski,D Karlen,G Duckeck,M J Goodrick,J M Roney,T Behnke,J Hagemann,M Jimack,C Stegmann,J Ludwig,A M Rossi,M Jones,J D Gillies,R P Middleton,A C Janissen,G M Dallavalle,J Lauber,P W Jeffreys,B Wilkens,T P Kokott,J Steuerer,B Nellen,P G Estabrooks,D C Imrie,D Axen,J Schwiening,J R Carter,D G Fong,A K Honma,A A Carter,R J Homer,G Vasseur,G Yekutieli,M Foucher,M Hansroul,J Mildenberger,N I Geddes,H Mes,A Skillman,R M Brown,P Kyberd,A Buijs,P Leblanc,R Bartoldus,V Gibson,R D Heuer,K Stephens,T J Mcmahon,N Tesch,W Mohr,J M Lorah,J P Martin,A Rollnik,J W Gary,F G Oakham,N J Tresilian,F X Gentit,O Schaile,H Przysiezniak,S W Gensler,W Schappert,J E Duboscq,R J Barlow,F Odorici,A T Watson,J Gascon,P M Watkins,R W Springer,M Cuffiani ,E Ros ,G Azuelos ,C Grandi ,L J Levinson ,S J De Jong ,M Turner ,P E.l Clarke ,C Sbarra ,Roberto Giacomelli ,E Etzion ,A Skuja ,D J.p Dumas ,H H Nguyen ,G Wolf ,H Von Der Schmitt ,T J Smith ,G Alexander ,W D Zeuner ,T R Wyatt ,G Quast ,J R Batley ,D L Wagner ,M Schröder ,J C Hart ,A H Ball ,G A Snow ,T Shears ,C Leroy ,H Burckhart ,U Müller ,J Von Krogh ,G Herten ,H Breuker ,C Schwick ,P F Harrison ,A Stahl ,S Kluth ,M Mori ,A Montanari ,K Kawagoe ,P Schenk ,J A Mckenna ,P Jovanović ,T Mori ,Roger Jones ,P Bright-Thomas ,S Marcellini ,J Becker ,M Cooper ,S L Lloyd ,S Komamiya ,D S Koetke ,T Włodek ,R Lahmann ,S J Hillier ,A M Lee ,R Van Kooten ,S Tarem ,A Martín ,P R Hobson ,P Igo‐Kemenes ,P Teixeira-Dias ,G Bella ,D G Charlton ,G Tranströmer ,R Keeler ,F Meijers ,R Ströhmer ,F Fabbri ,O Biebel ,G W Wilson ,J A Wilson ,S W O’neale ,E Do Couto E Silva ,D Strom ,H Jérémie ,B Schmitt ,S Dado ,G Mikenberg ,C H Shepherd-Themistocleous ,E Duchovni ,J King ,J Allison ,H M Fischer ,P Capiluppi ,J T Baines ,M G Rison ,M Weber ,S Arcelli ,D Robinson ,S A Wotton ,M Sasaki ,Ö Runólfsson ,D Lellouch ,Ch Geich-Gimbel ,J Letts ,M Fincke-Keeler ,S L Chu ,V H Winterer ,M J Pearce ,N Wermes ,G Hanson ,R Sobie ,G E Richards ,G Beaudoin ,L A Del Pozo ,A Wagner ,J Hobbs ,S Bethke ,J L Pinfold ,P Sherwood ,T Mäshimo ,X Lou ,E Torrente‐Lujan ,S Barnett ,H Evans ,M Dittmar ,Hiroshi Takeda ,Hui Deng ,D Van Den Plas ,J Král ,J Kroll ,C Jui ,S Towers ,M Mannelli ,T Takeshita ,D J Miller

doi:10.1007/bf01558388

Abstract

We have studied the reactionsγγ→μ + μ − andγγ→τ + τ − by measuring the properties of events of the typese + e −→e + e − μ + μ − ande + e −→e + e − τ + τ − ate + e − centre-of-mass energies between 88 and 94 GeV. The data sample corresponds to an integratede + e − luminosity of 40.4 pb−1 collected by the OPAL detector at LEP. The QED structure functionF 2 is extracted from a sample of 1462γγ→μ + μ − events in which one photon is off the mass shell (single-tagged). TheQ 2 range for these massive photons is 4–400 GeV2, with an averageQ 2 of 8 GeV2. We have observed 48e + e −→e + e − μ + μ − events in which both final state electrons are detected. In the sample of single-tag events we have identified 34.9±6.7 events as due to the reactionγ;→τ + τ −, on an estimated background of 5.1±2.7 events. In all cases the measured event distributions agree with QED calculations.

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