Study of CP asymmetries in charmless hadronic B decays: Toward a measurement of α

Abstract

We present preliminary measurements of time-dependent CP asymmetries in neutral B meson decays to π + π − and π + π − π 0 final states, where the latter is measured in the region of the Dalitz plane dominated by the ϱ resonance. We also present preliminary measurements of the branching fraction for the decay B + → π + π 0 and an improved upper limit for B 0 → π 0 π 0, both of which are needed to extract the CP parameter α from the time-dependent dependent CP asymmetry in the π + π − channel. These results are obtained from a data sample of approximately 88 million γ(4 S) → B B decays collected with the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC.