Measurement of the branching ratio forΥ’’→μμ

Abstract

Using the CUSB-II detector at the Cornell Electron Storage Ring, we have measured Bμμ, the branching fraction into muons, of the Υ’ ’ meson. We find ${\mathit{B}}_{\mathrm{\mu }\mathrm{\mu }}$(Υ’ ’)=(1.53±0.33±0.21)%, from which the Υ’ ’ total decay width is 25.5±5.0 keV. From this result we obtain ${\mathrm{\alpha }}_{\mathrm{s}}$=0.${170}_{\mathrm{-}0.012}^{+0.015\mathrm{}}$, ${\Lambda }_{\mathrm{MS}\mathrm{¯}{=148\mathrm{}}_{\mathrm{-}39}^{+56\mathrm{}}}$ MeV. (MS¯ denotes the modified minimal-subtraction scheme).