The nature of $f_0\left(S^{*}\right)$ is revealed by its pole structure in the complex energy plane. Data on $\pi \pi \to \pi \pi$, $\pi \pi \to K\overline{K}$, and $\mathrm{pp}\to \mathrm{pp}\pi \pi \left(K\overline{K}\right)$ in the neighborhood of the $K\overline{K}$ threshold are described by unitary amplitudes with at least one nearby pole, which sits on sheet II. However, we reiterate that results on $\frac{J}{\psi }\to \phi \pi \pi \left(K\overline{K}\right)$ decay require an additional nearby pole on sheet III, forcing the $f_0\left(S^{*}\right)$ to be narrow, in contradistinction to the very recent claims of Zou and Bugg.

• Received 5 August 1993

DOI:https://doi.org/10.1103/PhysRevD.48.5422