Measurement of B({upsilon}(5S){yields}B{sub s}{sup (*)}B{sub s}{sup (*)}) using {phi} mesons

Knowledge of the B{sub s} decay fraction of the {upsilon}(5S) resonance, f{sub S}, is important for B{sub s} meson studies at the {upsilon}(5S) energy. Using a data sample collected by the CLEO III detector at CESR consisting of 0.423 fb{sup -1} on the {upsilon}(5S) resonance, 6.34 fb{sup -1} on the {upsilon}(4S) and 2.32 fb{sup -1} in the continuum below the {upsilon}(4S), we measure B({upsilon}(5S){yields}{phi}X)=(13.8{+-}0.7{sub -1.5}{sup +2.3})% and B({upsilon}(4S){yields}{phi}X)=(7.1{+-}0.1{+-}0.6)%; the ratio of the two rates is (1.9{+-}0.1{sub -0.2}{sup +0.3}). This is the first measurement of the {phi} meson yield from the {upsilon}(5S). Using these rates, and a model dependent estimate of B(B{sub s}{yields}{phi}X), we determine f{sub S}=(24.6{+-}2.9{sub -5.3}{sup +11.0})%. We also update our previous independent measurement of f{sub S} made using the inclusive D{sub s} yields to now be (16.8{+-}2.6{sub -3.4}{sup +6.7})%, due to a better estimate of the number of hadronic events. We also report the total {upsilon}(5S) hadronic cross section above continuum to be {sigma}(e{sup +}e{sup -}{yields}{upsilon}(5S))=(0.301{+-}0.002{+-}0.039) nb. This allows us to extract the fraction of B mesons as (58.9{+-}10.0{+-}9.2)%, equal to 1-f{sub S}. Averaging the three methods gives a model dependent result of f{sub S}=(21{sub -3}{sup +6})%.