Radiative B Meson Decay as a Probe of Physics Beyond the Standard Model: Time-Dependent CP Violation in B0 → Ks0π0γ and the B → φKγ Branching Fraction

The author presents measurements of radiative B meson decays to the final states Ks0π0γ and Kφγ based on data collected at the Υ(4S) resonance with the BABAR detector at the PEP-II e+e- collider at SLAC. In a data sample of 467 million B(bar B) pairs, the time-dependent CP asymmetry in B0 → Ks0π0γ decays is measured in two regions of Ks0-π0 invariant mass. In the K* region, 0.8 < m(Ks0π0) < 1.0 GeV/c2, we find SK*γ = -0.03 ± 0.29 ± 0.03 and CK*γ = -0.14 ± 0.16 ± 0.03; in the range 1.1 < m(Ks0π0) < 1.8 GeV/c2, they find SK#sub s##sup 0#π#sup 0#γ = -0.78 ± 0.59 ± 0.09 and CK#sub s##sup 0#π#sup 0#γ = -0.36 ± 0.33 ± 0.04. With a sample of 228 million B(bar B) pairs they measure the branching fraction Β(B+ → K+φγ) = (3.5 ± 0.6 ± 0.4) x 10-6 and set the limit Β(B0 → K0φγ) < 2.7 x 10-6 at 90% confidence level. The direct CP asymmetry in B+ → K+φγ is found to be ACP = (-26 ± 14 ± 5)%. In each case the uncertainties are statistical and systematic, respectively