Observation of $1^{-}{0}^{-}$ Final States from $\psi (2S)$ Decays and $e^{+}{e}^{-}$ Annihilation

Using CLEO data collected from CESR $e^{+}{e}^{-}$ collisions at the $\psi (2S)$ resonance and nearby continuum at $\sqrt{s}=3.67\mathrm{G}\mathrm{e}\mathrm{V}$, we report the first significantly nonzero measurements of light vector-pseudoscalar hadron pair production (including $\rho \pi$, $\omega \pi$, $\rho \eta$, and $K^{*0}\overline{K^0}$) and the ${\pi }^{+}{\pi }^{-}{\pi }^0$ final state, both from $\psi (2S)$ decays and direct $e^{+}{e}^{-}$ annihilation.

Figure 1

Distributions of scaled visible energy, $E_{\mathrm{v}\mathrm{i}\mathrm{s}}/\sqrt{s}$, for labeled final states. Plots for $\rho \pi$ and $b_1\pi$ sum over the charged and neutral states. Histogram entries are shown for $\psi (2S)$ data (points with error bars), scaled continuum (shaded histogram), and MC (dashed line) with arbitrary normalization. The vertical arrows mark ends of signal selection ranges.

Figure 2

Invariant mass distributions relevant to the final states indicated, one entry per event. Symbols are defined in Fig. 1.

Figure 3

Invariant masses for the $K^{*}(892)$ (left) and $K_S^0$ (right) candidates, one entry per event, for the final states indicated. Symbols are defined in Fig. 1.

Figure 4

Distributions for the ${\pi }^{+}{\pi }^{-}{\pi }^0$ final state: the Dalitz plots for (a) $\psi (2S)$ and (b) continuum data; (c) the ${\pi }^{+}{\pi }^{-}$, ${\pi }^{+}{\pi }^0$, and ${\pi }^{-}{\pi }^0$ mass combinations ($3\mathrm{\text{entries}}/\mathrm{\text{event}}$), and (d) the $\gamma \gamma$ mass. Symbols are defined in Fig. 1.