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


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.


We perform a measurement of direct CP violation in b to sγ ACP, 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.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:particle physics; CP violation; CPV; B meson; BABAR; Radiative B Decay; Particle Identification; ECOC
Degree Grantor:California Institute of Technology
Division:Physics, Mathematics and Astronomy
Major Option:Physics
Awards:John Stager Stemple Memorial Prize in Physics, 2011.
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Hitlin, David G.
Thesis Committee:
  • Hitlin, David G. (chair)
  • Patterson, Ryan B.
  • Wise, Mark B.
  • Porter, Frank C.
Defense Date:1 May 2013
Record Number:CaltechTHESIS:05022013-152247133
Persistent URL:
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:7655
Deposited By: Piti Ongmongkolkul
Deposited On:08 May 2013 17:49
Last Modified:04 Oct 2019 00:00

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