Search for D to phi l nu and measurement of the branching fraction for D to phi pi

Abstract

Using a data sample of integrated luminosity of about 33 pb$^{-1}$ collected around 3.773 GeV with the BESII detector at the BEPC collider, the semileptonic decays $D^+ \to \phi e ^+\nu_e$, $D^+ \to \phi \mu^+\nu_\mu$ and the hadronic decay $D^+ \to \phi \pi^+$ are studied. The upper limits of the branching fractions are set to be $BF(D^+ \to \phi e ^+\nu_e) <$ 2.01% and $BF(D^+ \to \phi \mu^+ \nu_\mu) <$ 2.04% at the 90% confidence level. The ratio of the branching fractions for $D^+ \to \phi \pi^+$ relative to $D^+ \to K^-\pi^+\pi^+$ is measured to be $0.057 \pm 0.011 \pm 0.003$. In addition, the branching fraction for $D^+ \to \phi \pi^+$ is obtained to be $(5.2 \pm 1.0 \pm 0.4) \times 10^{-3}$.