Study of Three-Prong $τ$ Decays and Determination of the $A_{1}$ Parameters

Publisher Website

19 May 1986

journal article
research article
Published by American Physical Society (APS) in Physical Review Letters

Vol. 56 (20) , 2132-2135
https://doi.org/10.1103/physrevlett.56.2132

Abstract

We report the results of a study of the three-prong decay mode of the

τ

in data taken with the DELCO detector at the SLAC

e^{+} e^{-}

storage ring PEP. We determine the total three-prong branching ratio to be

B (3) = (12.1 \pm 0.5 \pm 1.2) %

and the exclusive branching ratios

B (τ \to π^{+} π^{-} π^{\pm} ν) = (5.0 \pm 0.1) %

and

B (τ \to π^{+} π^{-} π^{\pm} π^{0} ν) = (6.0 \pm 1.2) %

, respectively. The data with three charged pions allow for the determination of the mass and width of the

A_{1}

resonance as

M_{A_{1}} = 1056 \pm 20 \pm 15

MeV and

Γ_{A_{1}} = 476_{- 120}^{+ 132} \pm 54

MeV.

Keywords

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