Measurement of CP asymmetries and branching fractions in two-body neutral B meson decays to charged pions and kaons with the BABAR detector

This dissertation presents a measurement of CP asymmetries and branching fractions for neutral B meson decays to two-body final states of charged pions and kaons. The results are obtained from a data sample of about 88 million ϒ(4S) → BB¯ decays collected between 1999 and 2002 with the BABAR detector at the PEP-II asymmetric-energy B factory located at the Stanford Linear Accelerator Center. A fit to kinematic, topological, and particle identification information measures the charge-averaged branching fractions $B$(B0 → π+π −) = (4.7 ± 0.6 ± 0.2) × 10−6 and $B$(B₀ → K+π −) = (17.9 ± 0.9 ± 0.7) × 10−6 ; the 90% confidence level upper limit $B$(B₀ → K+ K−) < 0.6 × 10−6; and the direct CP-violating charge asymmetry $AKp$ = −0.102 ± 0.050 ± 0.016 [−0.188, −0.016], where the first uncertainties are statistical and the second are systematic and the ranges in square brackets indicate the 90% confidence interval. A fit which adds decay time and b-flavor tagging information measures the CP-violating parameters for B0 → π +π− decays S_ππ = 0.02 ± 0.34 ± 0.05 [−0.54, +0.58] and C_ππ = −0.30 ± 0.25 ± 0.04 [−0.72, +0.12].