Improved Measurement of cal{B}(D^+ --> mu^+ nu) and the Pseudoscalar Decay Constant f_{D^+}

TL;DR

This paper precisely measures the D+ meson decay constant by analyzing leptonic decay rates, providing important experimental data to compare with theoretical predictions and constraining new physics beyond the Standard Model.

Contribution

The study presents a more precise measurement of the D+ meson decay constant and sets a new upper limit on the electronic decay mode, improving previous experimental constraints.

Findings

Measured B(D+ -> mu+ nu) with improved precision

Determined fD+ to be approximately 223 MeV

Set an upper limit on B(D+ -> e+ nu) at 2.4 x 10^{-5}

Abstract

We extract a relatively precise value for the decay constant of the D+ meson by measuring B(D+ -> mu+ nu)=(4.40 +/- 0.66 {+0.09}{-0.12}) x 10^{-4}, using 281 inverse-pb of data taken on the psi(3770) resonance with the CLEO-c detector. We find fD+=(222.6 +/- 16.7 {+2.8}{-3.4}) MeV, and compare with current theoretical calculations. We also set a 90% confidence upper limit on B(D+ -> e+ nu)<2.4 x 10^{-5} which limits contributions from non-standard model physics.