Precision measurement of the \({\cal B}(\Upsilon(3S)\to\tau^+\tau^-)/{\cal B}(\Upsilon(3S)\to\mu^+\mu^-)\) ratio

• Published in: arXiv.org
• Main Authors: Lees, J P, Brown, D N, Koch, H, Hearty, C, Mattison, T S, So, R Y, Druzhinin, V P, Kozyrev, E A, Onuchin, A P, Serednyakov, S I, Skovpen, Yu I, K Yu Todyshev, Eisner, A M, Vazquez, W Panduro, Echenard, B, Miyashita, T S, Ongmongkolkul, P, Röhrken, M, Huard, Z, Pushpawela, B G, Wagner, S R, Bernard, D, Bettoni, D, Fioravanti, E, Garzia, I, Luppi, E, de Sangro, R, Finocchiaro, G, Martellotti, S, Patteri, P, Patrignani, C, Lacker, H M, Bhuyan, B, Cochran, J, Prell, S, Gritsan, A V, Lutz, A M, Lange, D J, Wright, D M, Hutchcroft, D E, Payne, D J, Cowan, G, Davis, C L, Denig, A G, Gradl, W, Hafner, A, Lafferty, G D, Seddon, R M, Neri, N, Palombo, F, Godang, R, Summers, D J, Taras, P, Raven, G, LoSecco, J M, Gaz, A, Margoni, M, Stroili, R, Bonneaud, G R, Chauveau, J, Casarosa, G, Chrzaszcz, M, Lusiani, A, Rama, M, Walsh, J J, Ferrarotto, F, Ferroni, F, Pilloni, A, Piredda, G, Waldi, R, Adye, T, Emery, S, Dorfan, J, Field, R C, Fulsom, B G, Hast, C, D W G S Leith, Luitz, S, Neal, H, Randle-Conde, A, Ahmed, H, Bellis, M, Burchat, P R, Puccio, E M T, Alam, M S, Guttman, N, Peimer, D R, Izen, J M, Gamba, D, Lanceri, L, Oyanguren, A, Albert, J, King, G J, Sibidanov, A, Sobie, R J, Tasneem, N, Harrison, P F, Latham, T E, Prepost, R, Wu, S L
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 10.05.2020
• Subjects: Mesons; Physics - High Energy Physics - Experiment; Quarks
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2005.01230

We report on a precision measurement of the ratio \({\cal R}_{\tau\mu}^{\Upsilon(3S)} = {\cal B}(\Upsilon(3S)\to\tau^+\tau^-)/{\cal B}(\Upsilon(3S)\to\mu^+\mu^-)\) 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 \(\Upsilon(3S)\) mesons. The ratio is measured to be \({\cal R}_{\tau\mu}^{\Upsilon(3S)} = 0.966 \pm 0.008_\mathrm{stat} \pm 0.014_\mathrm{syst}\) and is in agreement with the Standard Model prediction of 0.9948 within 2 standard deviations. The uncertainty in \({\cal R}_{\tau\mu}^{\Upsilon(3S)}\) is almost an order of magnitude smaller than the only previous measurement.