This paper gives results for the spectrum, all allowed E1 radiative partial widths (and some important M1 widths) and all open-charm strong decay amplitudes of all 40 cc states expected up to the mass of the 4S multiplet, just above 4.4 GeV. The spectrum and radiative widths are evaluated using two models, the relativized Godfrey-Isgur model and a nonrelativistic potential model. The electromagnetic transitions are evaluated using Coulomb plus linear plus smeared hyperfine wavefunctions, both in a nonrelativistic potential model and in the Godfrey-Isgur model. The open-flavor strong decay amplitudes are determined assuming harmonic oscillator wavefunctions and the 3 P0 decay model. This work is intended to motivate future experimental studies of highermass charmonia, and may be useful for the analysis of high-statistics data sets to be accumulated by the BES, CLEO and GSI facilities.

Open-flavor strong decays are mediated by qq pair production, which is known to occur dominantly with 3 P 0 quantum numbers. The relation of the phenomenological 3 P 0 model of these decays to ''microscopic'' QCD decay mechanisms has never been established clearly. In this paper we investigate qq meson decay amplitudes assuming pair production from the scalar confining interaction (sKs) and from one gluon exchange ͑OGE͒. sKs pair production predicts decay amplitudes of approximately the correct magnitude and D/S amplitude ratios in b 1 → and a 1 → which are close to experiment. The OGE decay amplitude is found to be subdominant in most cases, a notable exception being 3 P 0 → 1 S 0 ϩ 1 S 0 . The full sKs ϩ OGE amplitudes differ significantly from 3 P 0 model predictions in some channels and can be distinguished experimentally, for example, through an accurate comparison of the D/S amplitude ratios in b 1 → and a 1 →.

In this paper we survey all radial and orbital excitations of the Iϭ0 and Iϭ1 nn system anticipated up to 2.1 GeV. We give detailed predictions of their quasi-two-body branching fractions and identify characteristic decay modes that can isolate quarkonia; this should be useful in distinguishing quarkonia from glueballs and hybrids. Several of the ''missing mesons'' with L q q ϭ2 and L q q ϭ3 are predicted to decay dominantly into certain Sϩ P and SϩD modes, and should appear in experimental searches for hybrids in the same mass region. We also consider the topical issues of whether some of the recently discovered or controversial meson resonances, including glueball and hybrid candidates, can be accommodated as quarkonia.