Measurement of Time-Dependent CP Asymmetry in B0 --> KS pi0 gamma Decays

TL;DR

This study measures the time-dependent CP asymmetry in B0 decays to K_S0 pi0 gamma using a large data set, providing results consistent with the Standard Model within uncertainties.

Contribution

First measurement of CP asymmetry in B0 --> K_S0 pi0 gamma decays across different invariant mass regions using the full BABAR data set.

Findings

Measured CP asymmetry parameters with large uncertainties

Results are consistent with Standard Model predictions

Provides baseline for future precision measurements

Abstract

We measure the time-dependent CP asymmetry in B0 --> K_S0 pi0 gamma decays for two regions of K_S0-pi0 invariant mass, m(K_S0 pi0), using the final BABAR data set of 467 x 10^6 BBbar pairs collected at the PEP-II e+e- collider at SLAC. We find 339 +/- 24 B0 --> K*0 gamma candidates and measure S_{K* gamma} = -0.03 +/- 0.29 +/- 0.03 and C_{K* gamma} = -0.14 +/- 0.16 +/- 0.03. In the range 1.1 < m(K_S0 pi0) < 1.8 GeV/c^2 we find 133 +/- 20 B0 --> K_S0 pi0 gamma candidates and measure S_{K_S0 pi0 gamma} = -0.78 +/- 0.59 +/- 0.09 and C_{K_S0 pi0 gamma} = -0.36 +/- 0.33 +/- 0.04. The uncertainties are statistical and systematic, respectively.