Test of lepton universality in Υ(1S) decays at BABAR

• Published in: Physical review letters 2010-05, Vol.104 (19), p.191801-191801, Article 191801
• Main Authors: del Amo Sanchez, P, Lees, J P, Poireau, V, Prencipe, E, Tisserand, V, Garra Tico, J, Grauges, E, Martinelli, M, Palano, A, Pappagallo, M, Eigen, G, Stugu, B, Sun, L, Battaglia, M, Brown, D N, Hooberman, B, Kerth, L T, Kolomensky, Yu G, Lynch, G, Osipenkov, I L, Tanabe, T, Hawkes, C M, Soni, N, Watson, A T, Koch, H, Schroeder, T, Asgeirsson, D J, Hearty, C, Mattison, T S, McKenna, J A, Khan, A, Randle-Conde, A, Blinov, V E, Buzykaev, A R, Druzhinin, V P, Golubev, V B, Onuchin, A P, Serednyakov, S I, Skovpen, Yu I, Solodov, E P, Todyshev, K Yu, Yushkov, A N, Bondioli, M, Curry, S, Kirkby, D, Lankford, A J, Mandelkern, M, Martin, E C, Stoker, D P, Atmacan, H, Gary, J W, Liu, F, Long, O, Vitug, G M, Yasin, Z, Sharma, V, Campagnari, C, Hong, T M, Kovalskyi, D, Richman, J D, Eisner, A M, Heusch, C A, Kroseberg, J, Lockman, W S, Martinez, A J, Schalk, T, Schumm, B A, Seiden, A, Winstrom, L O, Cheng, C H, Doll, D A, Echenard, B, Hitlin, D G, Ongmongkolkul, P, Porter, F C, Rakitin, A Y, Andreassen, R, Dubrovin, M S, Mancinelli, G, Meadows, B T, Sokoloff, M D, Bloom, P C, Ford, W T, Gaz, A, Hirschauer, J F, Nagel, M, Nauenberg, U, Smith, J G, Wagner, S R, Ayad, R, Toki, W H, Hauke, A, Jasper, H, Karbach, T M, Merkel, J, Petzold, A, Spaan, B, Wacker, K, Kobel, M J, Schubert, K R
• Format: Article
• Language: English
• Subjects: ACCURACY; Experiment-HEP,HEPEX; HIGGS BOSONS; High Energy Physics - Experiment; LEPTONS; Leptons (Física nuclear); Leptons (Nuclear physics); Particles (Nuclear physics); Partícules (Física nuclear); Physics; PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; PSEUDOSCALARS; STANDARD MODEL
• ISSN: 0031-9007; 1079-7114
• DOI: 10.1103/PhysRevLett.104.191801

The ratio R(τμ)(Υ(1S))=Γ(Υ(1S)→τ+ τ-)/Γ(Υ(1S)→μ+ μ-) is measured using a sample of (121.8±1.2)×10(6)Υ(3S) events recorded by the BABAR detector. This measurement is intended as a test of lepton universality and as a search for a possible light pseudoscalar Higgs boson. In the standard model (SM) this ratio is expected to be close to 1. Any significant deviations would violate lepton universality and could be introduced by the coupling to a light pseudoscalar Higgs boson. The analysis studies the decays Υ(3S)→Υ(1S)π+ π-, Υ(1S)→l+ l-, where l=μ, τ. The result, R(τμ)(Υ(1S))=1.005±0.013(stat)±0.022(syst), shows no deviation from the expected SM value, while improving the precision with respect to previous measurements.