Structure Functions in the Decay $\tau^{\mp}\to \tau^{\mp}\pi^{0}\pi^{0}\nu_{\tau}$

TL;DR

This paper measures the structure functions in tau decay to three pions and a neutrino using CLEO II data, providing model-independent limits on non-axial-vector contributions and separating scalar and vector contributions.

Contribution

It presents the first measurement of structure functions in tau decay to three pions, with model-independent limits on non-axial-vector contributions and separation of scalar and vector components.

Findings

Non-axial-vector contributions are less than 16.6% of the total branching fraction.

Scalar contributions are less than 9.4%, vector contributions less than 7.3% at 95% confidence level.

Measured structure functions depend only on the three pion invariant mass.

Abstract

Using the CLEO II detector operating at the CESR e+e- collider, we have measured the structure functions in the decay tau+/- --> pi+/- pi0 pi0 nu, based on a sample corresponding to 4*10E6 produced tau-pair events. We determine the integrated structure functions, which depend only on the three pion invariant mass, as well as the structure functions differential in the Dalitz plot. We extract model independent limits on non-axial-vector contributions from the measured structure functions as less than 16.6% of the total branching fraction, at the 95% confidence level. Separating the non-axial-vector contributions into scalar and vector contributions, we measure that scalars (vectors) contribute with less than 9.4% (7.3%) to the total branching ratio, at the 95% confidence level.