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Open Access item Test of Lepton Universality in Y(1S) Decays at BABAR

Authors:Babar Collaboration
Azzolini, Virginia
López-March, Neus
Martínez-Vidal, Fernando
Milanés, Diego A.
Oyanguren, Arantza
Lees, J. P.
Sánchez, P. D.
Issue Date:14-May-2010
Publisher:American Physical Society
Citation:Physical Review Letters 104 (19): 191801 (2010)
Abstract:The ratio R-tau mu(Y(1S)) = Gamma Y(1S)->tau(+)tau(-)/Gamma(+)(-)(Y(1S)->mu)(mu) is measured using a sample of (121.8 +/- 1.2) x 10(6)Y(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 Y(3S) -> Y(1S)pi(+)pi(-), Y(1S) -> l(+)l(-), where l = mu, tau. The result, R-tau mu (Y(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.
Publisher version (URL):http://dx.doi.org/ 10.1103/PhysRevLett.104.191801
Appears in Collections:(IFIC) Artículos

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