Resonance structure of tau->Kpipi decays

TL;DR

This paper analyzes the resonance structure in tau->Kpipi decays using CLEO II data, measuring K1 resonance fractions, masses, widths, and the Ka-Kb mixing angle to understand decay dynamics.

Contribution

It provides new measurements of K1 resonance parameters and the Ka-Kb mixing angle in tau decays, with broader resonance widths supporting certain decay models.

Findings

Measured K1(1270) and K1(1400) fractions in tau decays.

Found K1 resonances broader than previous hadroproduction data.

Supported models with larger K1 widths explaining small tau->Kpipi branching fraction.

Abstract

Using a sample of 4.7/fb integrated luminosity accumulated with the CLEO II detector at the Cornell Electron Storage Ring (CESR), we investigate the mass spectrum and resonant structure in tau->Kpipi decays. We measure the relative fractions of K1(1270) and K1(1400) resonances in these decays, as well as the K1 masses and widths. Our fitted K1 resonances are somewhat broader than previous hadroproduction measurements, and in agreement with recent LEP results from tau decay. The larger central value of our measured width supports models which attribute the small tau->Kpipi branching fraction to larger K1 widths than are presently tabulated. We also determine the Ka-Kb mixing angle theta_K.