Measurement of CP Asymmetries and Branching Fractions in Neutral B Meson Decays to Charged Pions and Kaons with the BABAR Detector

Title of Dissertation: MEASUREMENT OF CP ASYMMETRIES AND BRANCHING FRACTIONS IN NEUTRAL B MESON DECAYS TO CHARGED PIONS AND KAONS WITH THE BABAR DETECTOR Amir Farbin, Doctor of Philosophy, 2003 Dissertation directed by: Professor Abolhassan Jawahery Department of Physics This disseration 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) → BB̄ 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 AKπ = −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 B → π+π− decays Sππ = 0.02±0.34±0.05 [−0.54,+0.58] and Cππ = −0.30±0.25±0.04 [−0.72,+0.12]. MEASUREMENT OF CP ASYMMETRIES AND BRANCHING FRACTIONS IN NEUTRAL B MESON DECAYS TO CHARGED PIONS AND KAONS WITH THE BABAR DETECTOR