Observation of B -> K^0_S pi^+ pi^- and B -> K^*(892) ^+- pi^-+ and measurement of the charge asymmetry in B -> K^*(892)^+- pi^-+

Abstract

We report on a search for charmless hadronic B decays to the three-body final states K 0 S h +- pi -+ , K +- h -+ pi 0 , and K 0 S h +- pi 0 (h +- denotes a charged pion or kaon), using 9.12 fb -1 of integrated luminosity produced at sqrt{s}=10.58 GeV and collected with the CLEO detector. We observe the decay B -> K 0 pi + pi - with a branching fraction (50 +10 -9 +-7)x10 -6 and the decay B -> K * (892) +- pi -+ with a branching fraction (16 +6 -5 +-2)x10 -6 , where the uncertainties are statistical and systematic, respectively. Both branching fractions are averages over CP-conjugate states. We also search for a CP-violating asymmetry in the decay B -> K * (892) +- pi -+ . We find A CP (B -> K * (892) +- pi -+ )=0.26 +0.33 -0.34 +0.10 -0.08 , giving an allowed interval of [-0.31,0.78] at the 90% confidence level. These measurements are used to constrain fundamental parameters of the Standard Model.