Measurement of the Form Factors for the Decay
D_s --> phi mu+ nu
by P.L. Frabetti et al.
Abstract.
Fermilab high-energy photoproduction experiment
E687 provides a sample of approximately 90 events of the decay mode
$D_s^+\rightarrow \phi\mu^+\nu$.
The ratios of the form factors governing the decay are measured to be
$R_v=1.8\pm 0.9\pm 0.2$ and
$R_2=1.1\pm 0.8\pm 0.1$, implying a polarization of
$\Gamma_l/\Gamma_t=1.0\pm 0.5\pm 0.1$ for the electron decay,
consistent with our measurement of the form factors for the
decay $D^+\rightarrow \overline{K}^{*0}\mu^+\nu$.