Test of Lepton Universality in Υ(1S) Decays at BABAR

• Main Authors: Fisher, Peter H. (Contributor), Dujmic, Denis (Contributor), Cowan, Ray Franklin (Contributor), Sciolla, Gabriella (Contributor), Yamamoto, R. K. (Contributor), Zhao, M. (Contributor)
• Other Authors: Massachusetts Institute of Technology. Department of Physics (Contributor), Massachusetts Institute of Technology. Laboratory for Nuclear Science (Contributor)
• Format: Article
• Language: English
• Published: American Physical Society, 2010-09-28T18:50:05Z.
• Subjects: Article
• Online Access: Get fulltext

The ratio Rtau mu(Υ(1S))=ΓΥ(1S)-->tau+tau-/GammaΥ(1S)-->mu+mu- is measured using a sample of (121.8±1.2)×10[superscript 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)pi+pi-, Υ(1S)→l+l-, where l=mu, tau. The result, Rtau mu(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.
United States. Dept. of Energy
National Science Foundation
Natural Sciences and Engineering Research Council of Canada
Commissariat à l'Energie Atomique (France)
Institut National de Physique Nucleaire et Physique des Particules/CNRS
Bundesministerium für Bildung und Forschung, Germany
Deutsche Forschungsgemeinschaft
Istituto Nazionale di Fisica Nucleare of Italy
FOM of the Netherlands
Norges forskningsråd
Ministry of Education and Science of the Russian Federation
MEC (Spain)
Science and Technology Facilities Council, United Kingdom
Alfred P. Sloan Foundation
Marie Curie Individual Fellowships