B(Ds^+ -> l^+ nu) and the Decay Constant f_(D_s^+)

TL;DR

This paper presents precise measurements of the decay constant f_{D_s^+} using leptonic decays of D_s^+ mesons, providing important tests for theoretical models of heavy meson decay dynamics.

Contribution

The study reports the final CLEO-c measurements of D_s^+ leptonic decay rates and determines the decay constant f_{D_s^+} with improved precision, including new results from tau decay channels.

Findings

Measured f_{D_s^+} = 275 +/- 10 +/- 5 MeV

Determined ratio f_{D_s^+}/f_{D^+} = 1.24 +/- 0.10 +/- 0.03

Provided experimental data consistent with theoretical predictions

Abstract

I report final CLEO-c results on the purely leptonic decays of the D_s^+ -> l^+ nu, for the cases when l^+ is a mu^+ or tau^+, when it decays into pi^+ anti-nu, using 314/pb of data at 4.170 GeV. I also include preliminary results from the tau^+ -> e^+ nu anti-nu channel using 195/pb. Combining both we measure f_{D_s}= 275 +/- 10 +/- 5 MeV, and f_{D_s^+}/{f_{D^+}=1.24 +/- 0.10 =/- 0.03 .