Time-dependent analysis of B0→K0Sπ−π+γ decays and studies of the K+π−π+ system in B+→K+π−π+γ decays

Abstract

We measure the time-dependent C P asymmetry in the radiative-penguin decay B 0 → K 0 S π − π + γ , using a sample of 471 × 10 6 Υ ( 4 S ) → B ¯ B events recorded with the BABAR detector at the PEP-II e + e − storage ring at SLAC. Using events with m K π π < 1.8 GeV / c 2 , we measure the branching fractions of B + → K + π − π + γ and B 0 → K 0 π − π + γ , the branching fractions of the kaonic resonances decaying to K + π − π + , as well as the overall branching fractions of the B + → ρ 0 K + γ , B + → K * 0 π + γ and S -wave B + → ( K π ) * 0 0 π + γ components. For events from the ρ mass band, we measure the C P -violating parameters S K 0 S π + π − γ = 0.14 ± 0.25 ± 0.03 and C K 0 S π + π − γ = − 0.39 ± 0.2 0 + 0.03 − 0.02 , where the first uncertainties are statistical and the second are systematic. We extract from this measurement the time-dependent C P asymmetry related to the C P eigenstate ρ 0 K 0 S and obtain S K 0 S ρ γ = − 0.18 ± 0.3 2 + 0.06 − 0.05 , which provides information on the photon polarization in the underlying b → s γ transition.