Precision Measurement of the Ratio B(ϒ(3S)→τ^{+}τ^{-})/B(ϒ(3S)→μ^{+}μ^{-})

• Published in: Physical review letters 2020-12, Vol.125 (24), p.241801-241801, Article 241801
• Main Authors: Lees, J P, Poireau, V, Tisserand, V, Grauges, E, Palano, A, Eigen, G, Brown, D N, Kolomensky, Yu G, Fritsch, M, Koch, H, Schroeder, T, Cheaib, R, Hearty, C, Mattison, T S, McKenna, J A, So, R Y, Blinov, V E, Buzykaev, A R, Druzhinin, V P, Golubev, V B, Kozyrev, E A, Kravchenko, E A, Onuchin, A P, Serednyakov, S I, Skovpen, Yu I, Solodov, E P, Todyshev, K Yu, Lankford, A J, Dey, B, Gary, J W, Long, O, Eisner, A M, Lockman, W S, Panduro Vazquez, W, Chao, D S, Cheng, C H, Echenard, B, Flood, K T, Hitlin, D G, Kim, J, Li, Y, Lin, D X, Miyashita, T S, Ongmongkolkul, P, Oyang, J, Porter, F C, Röhrken, M, Huard, Z, Meadows, B T, Pushpawela, B G, Sokoloff, M D, Sun, L, Smith, J G, Wagner, S R, Bernard, D, Verderi, M, Bettoni, D, Bozzi, C, Calabrese, R, Cibinetto, G, Fioravanti, E, Garzia, I, Luppi, E, Santoro, V, Calcaterra, A, de Sangro, R, Finocchiaro, G, Martellotti, S, Patteri, P, Peruzzi, I M, Piccolo, M, Rotondo, M, Zallo, A, Passaggio, S, Patrignani, C, Shuve, B J, Lacker, H M, Bhuyan, B, Mallik, U, Chen, C, Cochran, J, Prell, S, Gritsan, A V, Arnaud, N, Davier, M, Le Diberder, F, Lutz, A M, Wormser, G, Lange, D J, Wright, D M, Coleman, J P, Gabathuler, E, Hutchcroft, D E, Payne, D J, Touramanis, C, Bevan, A J, Di Lodovico, F, Sacco, R, Cowan, G, Banerjee, Sw
• Format: Article
• Language: English
• Subjects: Mesons; PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; Quarks
• ISSN: 0031-9007; 1079-7114
• DOI: 10.1103/PhysRevLett.125.241801

We report on a precision measurement of the ratio R_{τμ}^{ϒ(3S)}=B(ϒ(3S)→τ^{+}τ^{-})/B(ϒ(3S)→μ^{+}μ^{-}) using data collected with the BABAR detector at the SLAC PEP-II e^{+}e^{-} collider. The measurement is based on a 28  fb^{-1} data sample collected at a center-of-mass energy of 10.355 GeV corresponding to a sample of 122 million ϒ(3S) mesons. The ratio is measured to be R_{τμ}^{ϒ(3S)}=0.966±0.008_{stat}±0.014_{syst} and is in agreement with the standard model prediction of 0.9948 within 2 standard deviations. The uncertainty in R_{τμ}^{ϒ(3S)} is almost an order of magnitude smaller than the only previous measurement.