Measurement of time-dependent CP violation in B0→K0Sπ0π0 decays

Abstract

We report a measurement of time-dependent CP violation in B0→K0Sπ0π0 decays using a data sample of 772×106 B¯B pairs collected by the Belle experiment running at the Υ(4S) resonance at the KEKB e+e− collider. This decay proceeds mainly via a b→sd¯d “penguin” amplitude. The results are sin2ϕeff1=0.92+0.27−0.31 (stat.) ±0.11 (syst.) and A=0.28±0.21 (stat.) ±0.04 (syst.), which are the most precise measurements of CP violation in this decay mode to date. The value for the CP-violating parameter sin2ϕeff1 is consistent with that obtained using decay modes proceeding via a b→c¯cs “tree” amplitude.