B --> K⁰ pi⁺ pi^- and B --> K^*+ pi^-

Recent years have seen the first observations of several two-body charmless hadronic decays of B mesons, including the four B --> K pi transitions. These two-pseudoscalar decays have received considerable attention due to their expected role in improving our understanding of the weak interaction and in the extraction of the complex quark couplings described by the Cabibbo-Kobayashi-Maskawa matrix. The pseudoscalar-vector analogs of these decays, B --> K^*pi and K rho, provide further constraints on the magnitudes and phases of these couplings and present additional opportunities for observing direct CP violation and deviations from the Standard Model. Accurate measurement and interpretation of the rates and CP asymmetries of these quasi-two-body decays requires knowledge of the non-resonant contributions to the same final states.

We have employed a maximum likelihood technique to search for B decays to the three-pseudoscalar final states, K⁰_S h⁺ pi^-, K⁺ h^- pi⁰, and K⁰_S h⁺ pi⁰ (h^+/- denotes a charged pion or kaon), without regard for the resonant substructure. The only mode with a significant yield is B --> K⁰ pi⁺ pi^-, for which we calculate a branching fraction of (50 +10-9(stat.) +-7(syst.)) x 10e-6.

For each final state, we also search for two-body channels with intermediate vector resonances (K^*(892), K^*₀(1430), rho(770), and f₀(980)), as well as for non-resonant production. The only channel with an unabmiguous signal is B --> K^*+(892) pi^- with a branching fraction of (16 +6-5(stat.) +-2(syst.)) x 10e-6. Results for the K⁰_S h⁺ pi^- and K⁺ h^- pi⁰ topologies have been presented previously by the CLEO (hep-ex/9904008 and Phys. Rev. Lett.85:2881-2885,2000) and Belle (BELLE-CONF-0115, hep-ex/0205033, and hep-ex/0205062 Collaborations.

Observation of B --> K⁰ pi⁺ pi^- and B --> K^*+ pi^-
E. Eckhart et al.
Submitted to Phys. Rev. Lett.
CLNS 02/1789, CLEO 02-9 - SPIRES Search - hep-ex/0206024
Figure 1 - Figure 2