Measuring cal B(D^+ --> mu^+ nu) and the Pseudoscalar Decay Constant f_D^+

TL;DR

This paper reports a measurement of the branching fraction and decay constant of the D+ meson using data from the CLEO-c detector, providing important tests of theoretical models of heavy meson decays.

Contribution

First measurement of B(D+ -> mu+ nu) and f_D+ using data from the psi(3770) resonance with the CLEO-c detector.

Findings

Measured B(D+ -> mu+ nu) = (3.5 +/- 1.4 +/- 0.6) x10^(-4)

Determined f_D+ = 202 +/- 41 +/- 17 MeV

Sample contained 8 decay candidates with minimal background.

Abstract

In 60 inverse-pb of data taken on the psi(3770) resonance with the CLEO-c detector, we find 8 D+ -> mu+ nu decay candidates that are mostly signal, containing only 1 estimated background. Using this statistically compelling sample, we measure a value of B(D+ -> mu+ nu) = (3.5 +/- 1.4 +/- 0.6) x10^(-4), and determine fD+=(202 +/- 41 +/-17) MeV.