Study of CP-violating asymmetries in B-->pi^+/-pi^-/+, K^+/-pi^-+ decays

We present a preliminary measurement of the time-dependent CP-violating asymmetry parameters S_pipi and C_pipi in neutral B decays to the pi^+/-pi^-/+ CP eigenstate, and an updated preliminary measurement of the charge asymmetry A_Kpi in B --> K^+/-pi^-/+ decays. Event yields and $\CP$-violation parameters are determined simultaneously from a multidimensional unbinned maximum likelihood fit. In a data sample consisting of approximately 33 million Upsilon(4S)--)B-anti-B decays collected with the BABAR detector at the SLAC PEP-II asymmetric B Factory, we find 65^{+12}_{-11} pi^+/-pi^-/+ and 217+/-18 K^+/-pi^-/+ candidates and measure S_pipi = 0.03^{+0.53}_{-0.56}+/-0.11, C_pipi = -0.25^{+0.45}_{-0.47}+/-0.14, and A_Kpi = -0.07+/-0.08+/-0.02, where the first error is statistical and the second is systematic.