The European Physical Journal C

ISSN: 1434-6044 (printed version)
ISSN: 1434-6052 (electronic version)

Table of Contents

Abstract Volume 1 Issue 1/2 (1998) pp 201-209

theoretical physics:
Isospin violation in $\tau\rightarrow 3\pi\nu_\tau$

E. Mirkes, R. Urech

Institut für Theoretische Teilchenphysik, Universität Karlsruhe, D-76128 Karlsruhe, Germany

Received: 24 February 1997

Abstract. Isospin violating signals in the $\tau^-\rightarrow(3\pi)^-\nu_\tau$ decay mode are discussed. For the $\tau^-\rightarrow \pi^-\pi^-\pi^+\nu_\tau$ decay mode, isospin violation arises from the vector current contribution in the $\tau^-\rightarrow \omega\pi^-\nu_\tau$ decay with the subsequent isospin violating $\omega$ decay into $\pi^+\pi^-$. We demonstrate that such effects may be observed in presently available data through the measurement of the interference effects of these vector current contributions with the dominating axial vector current, i.e. through a measurement of the structure functions $W_F,W_G,W_H$ and $W_I$. In the case of the $\tau^- \to \pi^0 \pi^0 \pi^- \nu_\tau$ decay mode, a vector current contribution is generated by $\eta \pi^0$ mixing in the decay chain $\tau^- \to \eta \rho^- \nu_\tau \to \pi^0 \pi^0\pi^- \nu_\tau$. We find that this effect is rather small, the magnitude of the associated interference terms being too low for present statistics.

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Online publication: December 11, 1997
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