Time-dependent analysis of B[superscript 0] → K[0 over S]π[superscript −]π[superscript +]γ decays and studies of the K[superscript +]π[superscript −]π[superscript +] system in B[superscript +] → K[superscript +]π[superscript −]π[superscript +]γ decays

Abstract

We measure the time-dependent CP asymmetry in the radiative-penguin decay B[superscript 0] → K[0 over S]π[superscript -]π[superscript +]γ, using a sample of 471 × 10[superscript 6] ϒ(4S) → B[bar over B] events recorded with the BABAR detector at the PEP-II e[superscript +]e[superscript -] storage ring at SLAC. Using events with m[subscript Kππ] < 1.8 GeV/c[superscript 2], we measure the branching fractions of B[superscript +] → K[superscript +]π[superscript -]π[superscript +]γ and B[superscript 0] → K[superscript 0]π[superscript -]π[superscript +]γ, the branching fractions of the kaonic resonances decaying to K[superscript +]π[superscript -]π[superscript +], as well as the overall branching fractions of the B[superscript +] → ρ[superscript 0]K[superscript +]γ, B[superscript +] → K[superscript *0]π[superscript +]γ and S-wave B[superscript +] → (Kπ)[*0 over 0]π[superscript +]γ components. For events from the ρ mass band, we measure the CP-violating parameters S[subscript K[0 over S]π[superscript +]π[superscript -]γ] = 0.14 ± 0.25 ± 0.03 and C[subscript K[0 over S]π[superscript +]π[superscript -]γ] = -0.39 ± 0.20[+0.03 over -0.02], where the first uncertainties are statistical and the second are systematic. We extract from this measurement the time-dependent CP asymmetry related to the CP eigenstate ρ[superscript 0]K[0 over S] and obtain S[subscript K[0 over S]ργ] = -0.18 ± 0.32[+0.06 over -0.05], which provides information on the photon polarization in the underlying b → sγ transition.