Measurement of the branching fraction for the decay B^0 --> D^{*+}D^{*-}

Abstract

Decays of the type B --> D^{(*)} anti-D^{(*)} can be used to provide a measurement of the parameter sin2beta of the Unitarity Triangle that is complementary to the measurement derived from the mode B^0 --> J/psi K_s^0. In this document we report a measurement of the branching fraction for the decay B^0 --> D^{*+}D^{*-} with the BABAR detector. With data corresponding to an integrated luminosity of 20.7 fb^{-1} collected at the Upsilon(4S) resonance during 1999-2000, we have reconstructed 38 candidate signal events in the mode B^0 --> D^{*+}D^{*-} with an estimated background of 6.2+/-0.5 events. From these events, we determine the branching fraction to be BF(B^0 --> D^{*+}D^{*-}) = (8.0+/-1.6(stat)+/-1.2(syst))x10^{-4} (preliminary).