Masanobu Hirano

Relativistic Quarkonium Model Based on Instantaneous Ladder BS Equation. II -- Mass Levels of Charmonium and Bottonium--

The mass levels of the charm onium and the bottonium are calculated based on the in· stantaneous ladder BS equation. The agreement with experiment is fairly good. We get smaller as than nonrelativistic analyses. !l ms is estimated to be 80 ~ 130Me V. The relativistic effects are not so small in the charm onium.

Masses and OZI-Allowed Decay Widths of ϒ States in a Coupled Channel Model

A coupled channel model based on an effective quark interaction Hamiltonian and an OBE potential for meson-antimeson interactions is applied to the analysis of both masses and strong decay widths of Y states. It turns out to be quite successful, following the previous successful result for the ψ states. It is concluded that the effective quark interaction Hamiltonian fully explains dynamics not only for mass splitting but also for the Okubo- Zweig-Iizuka (OZI)allowed decay of heavy quarkonia. The most conspicuous prediction of the present model is the mass, ∼10.670 GeV, and the width, ∼20 MeV, of a yet unobserved Y (3D)resonance, which may correspond to the observed structure of the e + e − cross-section R seen in the energy range 10.6-10.8 GeV.

Systematization of q-q Mesons by the Bethe-Salpeter Equation

We investigate the spectra of the heavy and light quarkonia including the fine and hyperfine splittings by the potential taken into account the information from QeD in the asymptotic regions. To treat the light ones, we use the Bethe·Salpeter equation in the instantaneous ladder approximation with only Qositive ~nergy amplitude (PE). We show that the spectra of the heavy and light quar· konia can be reproduced well except for the hyperfine splitting of the light quark onium. It is noteworthy that the spectrum of heavy quark onium is almost determined by the asymptotic forms in the ultraviolet and infrared regions of the potential in our model.