Branching fractions and CP asymmetries in B-0 ->(K+K-KS0) and B+->(K+KSKS0)-K-0

We measure the branching fractions and CP asymmetries in the decays B-0 --> (K+K-KS0) and B+ --> (K+KSKS0)-K-0 using a sample of approximately 122 x 10(6) B(B) over bar pairs collected by the BABAR detector. From a time-dependent analysis of the (K+K-KS0) sample that excludes phiK(S)(0), the values of the CP-violation parameters are S = -0.56+/-0.25+/-0.04 and C = -0.10+/-0.19+/-0.10, where the first uncertainty is statistical and the second is systematic. We confirm that the final state is nearly purely CP even and extract the standard model parameter sin2beta = 0.57+/-0.26+/-0.04(-0)(+0.17) where the last error is due to uncertainty on the CP content. We present the first measurement of the CP-violating charge asymmetry A(CP)(B+ --> (K+KSKS0)-K-0) = -0.04+/-0.11+/-0.02. The branching fractions are B(B-0 --> (K+K-K0)) = (23.8+/-2.0+/-1.6) x 10(-6) and B(B+ --> (K+KSKS0)-K-0) = (10.7+/-1.2+/-1.0) x 10(-6).