Radiative B Meson Decay as a Probe of Physics Beyond the Standard Model: Time-Dependent CP Violation in B<super>0</super> → K<sub>S</sub> π<super>0</super> γ and the B → φ K γ Branching Fraction
Abstract
I present measurements of radiative B meson decays to the final states K<sub>S</sub> π<super>0</super> γ and K φ γ based on data collected at the Υ(4S) resonance with the BaBar detector at the PEP-II e<super>+</super>e<super>–</super> collider at SLAC. In a data sample of 467 million BBbar pairs, the time-dependent CP asymmetry in B<super>0</super> → K<sub>S</sub> π<super>0</super> γ decays is measured in two regions of K<sub>S</sub>-π<super>0</super> invariant mass. In the K* region, 0.8 < m(K<sub>S</sub> π<super>0</super>) < 1.0 GeV/c<super>2</super>, we find S<sub>K* γ</sub> = –0.03 ± 0.29 ± 0.03 and C<sub>K* γ</sub> = –0.14 ± 0.16 ± 0.03; in the range 1.1 < m(K<sub>S</sub> π<super>0</super>) < 1.8 GeV/c<super>2</super>, we find S<sub>KS π0 γ</sub> = –0.78 ± 0.59 ± 0.09 and C<sub>KS π0 γ</sub> = –0.36 ± 0.33 ± 0.04. With a sample of 228 million BBbar pairs we measure the branching fraction B(B<super>+</super> → K<super>+</super> φ γ) = (3.5 ± 0.6 ± 0.4) × 10<super>–6</super> and set the limit B(B<super>0</super> → K<super>0</super> φ γ) < 2.7 × 10<super>–6</super> at 90% confidence level. The direct CP asymmetry in B<super>+</super> → K<super>+</super> φ γ is found to be A<sub>CP</sub> = (–26 ± 14 ± 5)%. In each case the uncertainties are statistical and systematic, respectively.