A High Statistics Study of the Decay tau- -> pi- pi0 nu

TL;DR

This study measures the tau decay to pi- pi0 nu, providing precise branching fractions, mass spectra, and resonance parameters, and estimates its contribution to the muon's anomalous magnetic moment.

Contribution

It offers a high-statistics measurement of tau decay and detailed resonance analysis, improving understanding of hadronic effects in fundamental physics.

Findings

Branching fraction for tau- -> pi- pi0 nu is (25.15 +/- 0.04 +/- 0.31)%

Resonance parameters for rho(770), rho'(1450), and rho''(1700) are determined

Estimated hadronic contribution to muon g-2 from this decay spectrum

Abstract

We report a measurement of the branching fraction for tau- -> pi- pi0 nu and the invariant mass spectrum of the resulting pi- pi0 system using 72.2 /fb of data recorded by the Belle detector at the KEKB e+e- collider. The branching fraction obtained is (25.15 +/- 0.04 +/- 0.31)%, where the first error is statistical and the second is systematic. The unfolded pi- pi0 mass spectrum is used to determine resonance parameters for the rho(770), rho'(1450), and rho''(1700) mesons. We also use this spectrum to estimate the hadronic contribution to the anomalous magnetic moment of the muon.