Effects of the (rho, omega, phi) mixing on the dipion mass spectrum in e+ e- annihilation and tau decay

TL;DR

This paper investigates how mixing among rho, omega, and phi mesons due to isospin symmetry breaking can explain discrepancies in the pion form factor measurements between e+ e- annihilation and tau decays.

Contribution

It introduces a full mixing model of rho, omega, and phi mesons to explain the form factor differences, which was not considered in previous analyses.

Findings

Mixing explains the e+ e- and tau decay data discrepancy

Isospin 0 component appears inside the rho0 meson due to mixing

The model accounts for the mismatch below the phi mass

Abstract

A way to explain the puzzling difference between the pion form factor as measured in e+ e- annihilations and in tau decays is discussed. We show that isospin symmetry breaking, beside the already identified effects, produces also a full mixing between the rho0, omega and phi mesons which generates an isospin 0 component inside the rho0 meson. This effect, not accounted for in current treatments of the problem, seems able to account for the apparent mismatch between e+ e- and tau data below the phi mass.