Measurement of the time-dependent CP-violating asymmetry in $B^0\to K_s^0{\pi }^0\gamma$ decays

Abstract

We present a measurement of the time-dependent CP-violating asymmetry in $B^0\to K_0^{\ast }\gamma$ decays with $K_0^{\ast }\to K_s^0{\pi }^0$ based on 232 million ${\rm Y}(4\mathrm{S})\to B\bar{B}$ decays collected with the BaBar detector at the PEP-II asymmetric-energy $e^{+}{e}^{-}$ collider at SLAC. In a sample containing $157\pm 16$ signal decays, we measure $S_{K_0^{\ast }\gamma }=-0.21\pm 0.40\pm 0.05$ and $C_{K_0^{\ast }\gamma }=-0.40\pm 0.23\pm 0.03$, where the first error is statistical and the second systematic. We also explore $B^0\to K_s^0{\pi }^0\gamma$ decays with $1.1<m_{K_s^0{\pi }^0}<1.8$ GeV$/c^2$ and find $59\pm 13$ signal events with $S_{K_s^0{\pi }^0}=0.9\pm 1.0\pm 0.2$ and $C_{K_s^0{\pi }^0}=-1.0\pm 0.5\pm 0.2$.

8 pages, 7 postscript figures, submitted to PRD-RC