Charmless 2-and 3-body B Decays and the Angle Α(φ 2 )

We present preliminary measurements of branching fractions and CP -asymmetry parameters in twoand three-body charmless hadronic B decays. The available data sample consists of 227 million Υ (4S) → BB decays collected with the BABAR detector at the PEP-II asymmetric-energy e+e− collider at SLAC. We establish the observation of the decays B → ππ and B → KK and constrain the CKM angle α with a full SU(2) isospin analysis in the B → ππ system and with a B → π+π−π0 time-dependent Dalitz plot analysis. Contributed to the Proceedings of the 32nd International Conference on High Energy Physics, ICHEP’04, 16 August — 22 August 2004, Beijing, China Stanford Linear Accelerator Center, Stanford University, Stanford, CA 94309 Work supported in part by Department of Energy contract DE-AC02-76SF00515.