decays.

PACS numbers: 13.25.Gv, 13.20.Gd, 14.40.Gx, 12.39.Jh

Introduction
============

The lowest resonance in electron-positron collisions above charmed particle pair production threshold is the $\ppp = \psi(3770)$, discovered somewhat after the $J/\psi(3097)$ and the $\pp = \psi(3686)$ [@Rap].[^3] It provides a rich source of $D^0 \od$ and $D^+ D^-$ pairs, as anticipated theoretically [@Eetal]. The largest data sample of $\ppp$ decays studied so far, by the Mark III Collaboration at the Stanford electron-positron collider SPEAR [@MkIII], has been $9.56 \pm
0.48$ pb$^{-1}$. Plans are under way to accumulate as much as 3 fb$^{-1}$ at the Cornell Electron Storage Ring (CESR), which will permit much more incisive tests of a number of open questions [@Wkshp]. In the present note we discuss several of these which involve observation of [*non-charmed final states*]{} of the $\ppp$. These have been studied in two previous Ph. D. theses [@Zhu; @Walid] based on the Mark III data.

The $\ppp$ is the only present candidate for a D-wave $(l = 2)$ quarkonium level. (Strategies for finding the corresponding $b \bar b$ levels have been noted in Refs. [@KR; @GRD].) Although it is primarily $c \bar
c(1^3D_1)$, [^4] its leptonic width (quoted in Table I [@MkIII; @PDG]) indicates a 