The "forbidden" decays of hybrid mesons to $\pi \rho$ can be large

Abstract

The observation of ${\pi }_1(1600)\to \pi \rho$ is shown in the flux-tube model to be compatible with this state being a hybrid meson with branching ratio to this channel $\sim 30$. The $\pi \rho$ widths of other hybrids are related by rather general arguments. These results enable cross sections for photoproduction of hybrids to be predicted.

Comments: Replaced with revised version correcting a technical mistake, conclusions remain unchanged. Accepted for publication in PRD