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Measurement of Ds+ to mu+ nu and the Decay constant fDs

M. Artuso, CLEO Collaboration

hep-exarXiv:hep-ex/0607074

Abstract

We examine e+e- to Ds- Ds*+ or Ds-* Ds+ collisions at 4170 MeV using the CLEO-c detector in order to measure the decay constant fDs+. We use the Ds+ to ell+ nu channel, where the ell+ designates either a mu+ or a tau+. Analyzing both modes simultaneously, we determine B(Ds+ to mu+ nu)= (0.657 +- 0.090 +- 0.028)%, B(Ds+ to tau+ nu)= (7.1 +- 1.4 +- 0.3)%, and extract fDs+ = 282 +- 16 +- 7 MeV. Combining with our previous determination of B(D+ to mu+ nu), we find that the ratio fDs+/fD+ = 1.27 +- 0.12 +- 0.03. (All new results here are preliminary.) We compare with current theoretical estimates.

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