Hunting a hidden hadron: Is there a scalar glueball below 1 GeV?

Abstract

The answer to the question in the title is "probably not." But if there is, it must either lie above 600 MeV with a width less than 2 MeV or it must lie near 650 MeV and conspire with a $Q^2{\bar{Q}}^2$ state to appear very narrow in $\pi -\pi$ scattering. It should be hunted by studying the $\pi \pi$ spectrum in ${\Upsilon }^{\prime \prime }\to \Upsilon \pi \pi$ or $\frac{J}{\psi }\to \phi \pi \pi$.