Measurement of the Pseudoscalar Decay Constant fDs Using Charm-Tagged Events in e+e- Collisions at \sqrt{s}=10.58GeV

TL;DR

This paper measures the decay constant f_{D_s} by analyzing charm-tagged e+e- collision data, providing a precise value that enhances understanding of meson decay properties.

Contribution

First measurement of f_{D_s} using charm-tagged events at .58 GeV with detailed error analysis and improved precision over previous results.

Findings

Measured f_{D_s} = (283 b1 17 b1 7 b1 14) MeV

Determined the ratio .143 b1 0.018 b1 0.006 for decay widths

Isolated 489 b1 55 leptonic decay events

Abstract

Using 230.2 fb^(-1) of e+e- annihilation data collected with the BABAR detector at and near the peak of the Y(4S) resonance, 489 +/- 55 events containing the pure leptonic decay D_s^+ --> mu^+ nu_mu have been isolated in charm-tagged events. The ratio of partial widths Gamma(D_s^+ --> mu^+ nu_mu)/Gamma(D_s^+ --> phi pi^+) is measured to be 0.143 +/- 0.018 +/- 0.006 allowing a determination of the pseudoscalar decay constant f_{D_s} = (283 +/- 17 +/- 7 +/- 14) MeV. The errors are statistical, systematic, and from the D_s^+ --> phi pi^+ branching ratio, respectively.