Recent results of Υ spectroscopy with CUSB-II

Recent results obtained with the new CUSB-II bismuth germanate detector on Υ(3S) spectroscopy are presented. The CUSB-II detector is located at the Cornell Electron Storage Ring. From a new accurate measurement of the branching ratio Υ(3S) → μμ, we have determined the total width of the Υ(3S) state to be 25±5 (keV), and the ratio of widths Γggg/Γμμ to be 28.6+8.2-5.6, from which we are able to extract the value of the running coupling constant αs, and the QCD scale parameter ΛMS. These new values are consistent with the values determined from Bμμ for the Υ(1S) and the Υ(2S), which are also presented. The excellent electromagnetic energy resolution of the CUSB-II detector permits us to study the fine structure of the Υ(2P) state through the electric dipole (E1) photon transitions from the Υ(3S). The fine structure of the 2P state has been measured in both inclusive photon spectra, and in the exclusive events of the type Υ(3S) → γ+Υ(23PJ) → γγΥ(2S or 1S) → γγll, where the leptons are either electrons or muons. The measured branching ratios have been used to provide the first indirect measurement of the hadronic widths of the 2P states, and the measured fine structure has been used to place constraints on the spin dependence of the interquark potential