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 $D^+\rightarrow \overline{K}^{*0}\mu^+\nu$.