The CLEO III experiment has recently accumulated a large statistics sample of 4.73 · 106 Υ(3S) decays. We present the first evidence for the production of the triplet Υ(1D) states in the four-photon cascade, Υ(3S) → Υχb(2P), χb(2P) → γΥ(1D), Υ(1D) → γχb(1P), χb(1P) → γΥ(1S), followed by the Υ(1S) annihilation to e+e- or μ+μ-. We have also analyzed two-photon cascades between the triplet S and triplet P states and report improved measurements of the photon energies and transition rates. We have searched for Υ(3S) → γηb(1S) hindered M1 photon transition in inclusive photon spectrum. No evidence for such a transition is found. We set upper limits on the branching ratio, which rule out many previously published phenomenological estimates of the rate for this transition.
ASJC Scopus subject areas
- Atomic and Molecular Physics, and Optics
- Nuclear and High Energy Physics