$\eta \gamma Z$ anomaly from the $\eta -->\gamma \mu +\mu -$ decay

Abstract

We show that the $\eta \gamma Z$ anomaly can be measured by analysing parity-violating effects in the $\eta -->\gamma \mu +\mu -$ decay. In this sense, we find that the longitudinal polarization of the outgoing ${\mu }^{+}$ is an appropriate observable to be considered in future high-statistics $\eta$ factories. The effect is expected to lie in the range $10^{-5}-10^{-6}$ in the Standard Model.

Comments: 9 pages incl. 2 eps figures, REVTeX