G. Glaser

Determination of

AbstractUsing the Crystal Ball detector operating at the DORIS II storage ring we have measured the leptonic partial widthsГee of the Υ(1S) and Υ(2S) resonances. We find

) of the

\Gamma _{ee} (\Upsilon (1S)) = 1.34 \pm 0.03 \pm 0.06keV

(1s) and

and

(2s) Resonances and Measurement of R at

\Gamma _{ee} (\Upsilon (2S)) = 0.56 \pm 0.04 \pm 0.02keV.

.39-{GeV}

The effect onГee of applying different prescriptions for radiative corrections is discussed. We also measureR, the ratio of non-resonant hadronic cross section to the Born cross section of μ pair production, at c.m. energyW=9.39 GeV to beR=3.48±0.04±0.16.

Measurement of the branching ratios for the decays τ→hadron π0ν and τ→hadron π0π0ν

Abstract The Crystal Ball detector at the DORIS II storage ring at DESY has been used to measure the branching ratios for the decay modes τ ± →h ± π 0 ν and τ ± →h ± π 0 π 0 ν , where h ± is any charged hadron. The results are BR( τ ± → h ± π 0 ν ) = (22.0±0.8±1.9)%, BR( τ ± → h ± π 0 π 0 ν ) = (5.7±0.5 +1.0 −1.7 )%. The first result is in good agreement with the present world average. The decay mode h ± π 0 π 0 ν is reconstructed in τ decays for the first time. Its branching ratio, however, is somewhat lower than the corresponding world average, and therefore tends to increase the one-prong problem.