First Results from CLEO-c at E_cm=Psi(3770)

Abstract

The CLEO-c detector at CESR has begun to collect large data sets of $e^+e^- \to c\bar{c}$ events in the center-of-mass energy range $\sqrt{s}=3 - 5 $GeV that will greatly enhance the size of the world's data sets of events produced at charm threshold. Preliminary results for the pseudoscalar decay constant $f_{D^+}$ and absolute D-meson hadronic branching fractions from an initial integrated luminosity ${\cal L}=57 {\rm pb^{-1}}$ collected at $\sqrt{s}=\Psi(3770)$ are described. These charm measurements are also relevant for B physics.