Measurement of the Absolute Branching Fraction of D_s^+ --> tau^+ nu_tau Decay

TL;DR

This paper measures the absolute branching fraction of D_s^+ decaying to tau^+ nu_tau and determines the decay constant f_{D_s} using data from e+e- collisions with the CLEO-c detector, providing precise experimental results.

Contribution

First measurement of the absolute branching fraction of D_s^+ to tau^+ nu_tau and the decay constant f_{D_s} using CLEO-c data near the D_s production energy.

Findings

Branching fraction B(D_s^+ to tau^+ nu_tau) = (6.17 +- 0.71 +- 0.34)%

Decay constant f_{D_s} = (274 +- 10 +- 5) MeV

Results improve precision of D_s decay parameters

Abstract

Using a sample of tagged D_s decays collected near the D^*_s D_s peak production energy in e+e- collisions with the CLEO-c detector, we study the leptonic decay D^+_s to tau^+ nu_tau via the decay channel tau^+ to e^+ nu_e bar{nu}_tau. We measure B(D^+_s to tau^+ nu_tau) = (6.17 +- 0.71 +- 0.34) %, where the first error is statistical and the second systematic. Combining this result with our measurements of D^+_s to mu^+ nu_mu and D^+_s to tau^+ nu_tau (via tau^+ to pi^+ bar{nu}_tau), we determine f_{D_s} = (274 +- 10 +- 5) MeV.