Jul 16 – 22, 2009
Kraków, Poland
Europe/Warsaw timezone

Selected electroweak results using tau leptons at BaBar

Jul 17, 2009, 3:39 PM
Middle Lecture Hall A (Kraków, Poland)

Middle Lecture Hall A

Kraków, Poland

The Auditorium Maximum of the Jagiellonian University 33 Krupnicza Street 31-123 Kraków
Standard Model Electroweak Physics VII. Standard Model Electroweak Physics


Ms Elisa Guido (INFN & University Genova)


A selection of electroweak measurements performed by the BaBar experiment operating at the Stanford Linear Accelerator Center is presented. Using a sample of 122 million Y(3S) decays, we measure the ratio R = BR(Y(1S) -> tautau)/BR(Y(1S) -> mumu); the measurement is intended as a test of the lepton universality and as a search for a light pseudoscalar Higgs boson in NMSSM scenarios. Such a boson could appear in a deviation of the ratio R from 1. The analysis exploits the decays Y(3S) -> Y(1S)pi+pi-, Y(1S) -> l+l-, where l=mu,tau. We also present a search for the non-conservation of lepton flavor in the decay tau -> mu/e gamma performed with 967 M tau decays from e+e- annihilations at a center-of-mass energy corresponding to Y(2S), Y(3S) and Y(4S) resonances. Two additional results are based only on data recorded by BaBar at the Y(4S) resonance. The first result is a precision measurement of the mass of the tau lepton using 423 fb-1 of data. Using a pseudomass endpoint method, we determine the tau mass and we also measure the mass difference between the tau+ and tau-. Finally, precise measurements of the tau- -> KS0 pi- (pi0) nu_tau branching fraction and hadronic mass distribution are made using ~ 384 fb-1 of data. The mass and width of K*(892)- meson are found to be significantly different from PDG averages from those found in hadroproduction but are consistent with the recent measurements made by Belle using the same tau decay mode as considered here.

Primary author

Ms Elisa Guido (INFN & University Genova)

Presentation materials