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Measurement of Tau branching ratios

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Zeitschrift für Physik C Particles and Fields

Abstract

Using the data accumulated at LEP in 1989 and 1990 with the ALEPH detector, the inclusive and exclusive branching ratios of the τ lepton have been measured assuming lepton universality inZ 0 decays. The inclusive branching fractions for the τ decay into one, three, and five charged particles have been determined to be (85.45±0.97)%, (14.35±0.48)%, and (0.10±0.05)%, respectively, in agreement with the world averages. New undetected decay modes are determined to have a branching fraction of less than 2.1% at 95% CL. The measured branching ratios for quasi-exclusive channels are slightly larger than, but consistent with the world averages, except for the modes τ→3 hadrons+v τ andτ→hadron+2π0 v τ , which are significantly larger. These latter branching ratios have been found to be (9.5±0.7)% and (10.2±1.1)%, respectively. The sum of all the measured quasi-exclusive branching ratios is (100.4±1.8)%. A fully exclusive analysis of modes with neutral pions shows no evidence for new photonic decay modes with a branching fraction limit of 3.4% at 95% CL.

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Supported by CAICYT, Spain

Supported by the National Science Foundation of China

Supported by the Danish Natural Science Research Council

Supported by the UK Science and Engineering Research Council

Supported by the US Department of Energy, contract DE-AC02-76ER00881

Supported by the US Department of Energy, contract DE-FG05-87ER40319

Supported by the NSF, contract PHY-8451274

Supported by the US Department of Energy, contract DE-FC0S-85ER250000

Supported by SLOAN fellowship, contract BR2703

Supported by the Bundesministerium für Forschung und Technologic, Fed. Rep. of Germany

Supported by the Institut de Recherche Fondamentale du C.E.A

Supported by Fonds zur Förderung der wissenschaftlichen Forschung, Austria

Supported by the Korean Science and Engineering Foundation and Ministry of Education

Supported by the World Laboratory

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ALEPH Collaboration., Decamp, D., Deschizeaux, B. et al. Measurement of Tau branching ratios. Z. Phys. C - Particles and Fields 54, 211–228 (1992). https://doi.org/10.1007/BF01566649

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  • DOI: https://doi.org/10.1007/BF01566649

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