A study of the decays of tau on the Z resonance at LEP*
P. Abreu,W. Adam,T. Adye,E. Agasi,G. D. Alekseev,P. Allen,S. Almehed,S. J. Alvsvaag,U. Amaldi,E. G. Anassontzis,A. Andreazza,P. Antilogus,R. J. Apsimon,B. Asman,A. Augustinus,P. Baillon,P. Bambade,F. Barao,R. Barate,G. Barbiellini,D. Y. Bardin,A. Baroncelli,J. A. Barrio,W. Bart,M. J. Bates,M. Battaglia,M. Baubillier,K.-H. Becks,C. J. Beeston,M. Begalli,P. Beilliere,Yu. Belokopytov,P. Beltran,D. Benedic,M. Berggren,D. Bertrand,F. Bianchi,M. S. Bilenky,P. Billoir,J. Bjarne,D. Bloch,S. Blyth,V. Bocci,P. N. Bogolubov,T. Bolognese,M. Bonesini,W. Bonivento,P. S. L. Booth,P. Borgeaud,G. Borisov,H. Borner,C. Bosio,B. Bostjancic,S. Bosworth,O. Bother,T. J. V. Bowcock,S. Braibant,P. Branchini,K. D. Brand,R. A. Brenner,H. Briand,C. Bricman,R. C. A. Brown,N. Brummer,J.-M. Brunet,L. Bugge,H. Burmeister,J. A. M. A. Buytaert,M. Caccia,M. Calvi,A. J. Camacho,Rozas,T. Camporesi,V. Canale,F. Cao,F. Carena,L. Carrolt,E. Castelli,M. V. Castillo Gimenez,A. Cattai,L. Cerrito,Ph. Charpentier,L. Chaussard,J. Chauveau,P. Checchia,G. A. Chelkov,L. Chevalier,P. Chliapnikov,V. Chorowicz,J. T. M. Chrin,R. Cirio,M. P. Clara,P. Collins,J. L. Contreras,E. Cortina,G. Cosme,F. Couchot,D. Crennel,M. Crozon,J. Cuevas Maestro,S. Czellar,S. Dagoret,E. Dahl-Jensen,B. Dalmagne,G. Damgaard,G. Darbo,E. Daubie,A. Daum,P. D. Dauncey,M. Davenport,P. David,W. Da Silva,C. Defoix,D. Delikaris,B. A. Della Riccia,S. Delorme,P. Delpierre,N. Demaria,A. De Angelis,M. De Beer,H. De Boeck,W. De Boer,C. De Clercq,M. D. M. De Fez Laso,N. De Groot,C. De La Vaissiere,B. De Lotto,A. De Min,H. Dijkstra,L. Di Ciaccio,F. Djama,J. Dolbeau,M. Donszelmann,K. Doroba,M. Dracos,J. Drees,M. Dris,Y. Dufour,P. A.-M. Eerola,R. Ehret,T. Ekelo,G. Ekspong,A. Elliot Peisert,J.-P. Engel,D. Fassouliotis,T. A. Fearnley,M. Feindt,A. Fenyuk,M. Fernandez Alonso,A. Ferrer,T. A. Filippas,H. Foeth,E. Fokitis,P. Frenkiel,D. C. Fries,A. G. Frodesen,R. Fruhwirth,K. Furnival,J. Fuster,G. Galeazzi,D. Gamba,C. Garcia,J. Garcia,C. Gaspar,U. Gasparini,Ph. Gavillet,E. N. Gazis,J.-P. Gerber,P. Giacomelli,R. Gokieli,B. Golob,V. M. Golovatyuk,J. J. Gomez Y Cadenas,A. Goobar,G. Gopa,M. Gorski,A. Grant,F. Grard,E. Graziani,G. Grosadidier,P. Grosse-Wiesmann,B. Grossetete,S. Gumenyuk,J. Guy,U. Haedinger,F. Hahn,M. Hahn,S. Haider,A. Hakansson,A. Hallgren,K. Hamacher,G. Hamel De Monchenault,W. Hao,F. J. Harris,T. Henkes,J. J. Hernandez,P. Herquet,T. L. Hessing,H. J. Hilke,S. D. Hodgson,T. Hofmok,D. Holthuizen,P. F. Honore,J. E. Hooper,M. Houlden,P. O. Hulth,K. Hultqvist,P. Ioannou,D. Isenhower,P.-S. Iversen,J. N. Jackson,P. Jarry,E. K. Johansson,D. Johnson,L. Jonsson,G. Kalkanis,G. Kalmus,F. Kapusta,M. Karlsson,E. Karvelas,S. Katsanevas,E. C. Katsoufis,R. Keranen,J. Kesteman,B. A. Khomenko,H. Klein,W. Klempt,A. Klovning,P. Kluit,P. Kokkinias,M. Kopf,K. Korcyl,A. V. Korytov,V. Kostioukhine,C. Kourkoumelis,O. Kouznetsov,P. H. Kramer,J. Krolikowski,I. Kronkvist,J. Krstic,U. Kruener-Marquis,W. Krupinski,K. Kulka,K. Kurvinen,C. Lacasta,C. Lambropoulos,J. W. Lamsa,L. Lanceri,V. Lapin,R. Lauhakangas,G. Leder,R. Leitner,Y. Lemoigne,J. Lemonne,G. Lenzen,V. Lepeltier,J. M. Levy,E. Lieb,D. Liko,E. Lillethun,R. Lindner,A. Lipniacka,B. Loerstad,M. Lokajicek,J. G. Loken,M. A. Lopez Aguera,M. Los,D. Loukas,J. J. Lozano,P. Lutz,L. Lyons,G. Maehlum,J. Maillard,A. Maltezos,J. Marco,M. Margoni,J.-C. Marin,A. Markou,F. Matorras,C. Matteuzzi,G. Matthiae,M. McCubbin,W. T. Meyer,M. Michelotto,I. Mikulec,W. A. Mitaroff,W. J. Murray,B. Muryn,G. Myatt,F. Naraghi,P. Negri,B. Nijjhar,P. Niss,R. Orava,A. Ostankov,K. Osterberg,A. Ouraou,M. Paganoni,L. Pape,A. Passeri
semanticscholar（2017）
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摘要
F rom the analysis of a data sample corresponding to an integrated luminosity of 4.63 pb -1 taken during the 1990 run of LEP at centre of mass energies between 88.2GeV an 94.2GeV, the tau decays r ~ e g e v T , r -* ,u-~ .v~ , r ~ z c ( K ) v T , r r p v ~ and their charge conjugates have been studied. The following branching ratios have been measured; B R ( r ~ e aTeVT) = 18.6 + 0.8 (stat.) _ 0.6 (sys.)%, BR (z---+ /~17u vT) = 17.4 • 0.7 + 0.6%, B R ( r ~ z c ( K ) v T ) = 11.9_+0.7_ 0.7%, BR ( r > p vT) = 22.4 + 0.8 + 1.3%, in good agreement with world averages. The measured electronic and muonic branching ratios lead to a measurement of the strong coupling constant, es (mT) = 0.26 + 0.09 Extrapolating the c L value from -0 .12" m T to m z yields cL(mz)=0 .109 +0.012 0.028" The average polarization P~ of taus produced in Z---, r + r decays has also been measured using the above decay modes. The weighted mean of the polarizations obtained from the four decay modes is PT = 0.24 _+ 0.07. This value of PT gives, in the improved Born approximation, a ratio between the axial and vector coupling constants of the tau of vT/aT=0.12+__O.04, and hence a value of the effective electroweak mixing parameter sin 2 0 w(m~) = 0.220 _ 0.009.
