Measurement of the Direct CP Asymmetry in b→sγ via Sum of Exclusive B Meson Decays Using the BABAR Detector

Citation

Ongmongkolkul, Piti (2013) Measurement of the Direct CP Asymmetry in b→sγ via Sum of Exclusive B Meson Decays Using the BABAR Detector. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/ZNVN-R508. https://resolver.caltech.edu/CaltechTHESIS:05022013-152247133

Abstract

We perform a measurement of direct CP violation in b to sγ A_CP, and the measurement of a difference between Acp for neutral B and charged B mesons, Delta A_{X_s\gamma}, using 429 inverse femtobarn of data recorded at the Upsilon(4S) resonance with the BABAR detector. B mesons are reconstructed from 16 exclusive final states. Particle identification is done using an algorithm based on Error Correcting Output Code with an exhaustive matrix. Background rejection and best candidate selection are done using two decision tree-based classifiers. We found $\acp = 1.73%+-1.93%+-1.02% and Delta A_X_sγ = 4.97%+-3.90%+-1.45% where the uncertainties are statistical and systematic respectively. Based on the measured value of Delta A_X_sgamma, we determine a 90% confidence interval for Im C_8g/C_7gamma, where C_7gamma and C_8g are Wilson coefficients for New Physics amplitudes, at -1.64 < Im C_8g/C_7gamma < 6.52.

Thesis Files