Bottomonium studies via Υ(3S) decays. First observation of Υ(1D) states

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) → Υχ_b(2P), χ_b(2P) → γΥ(1D), Υ(1D) → γχ_b(1P), χ_b(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) → γη_b(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.