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,
K^{0}_{S} h^{+} pi^{-},
K^{+} h^{-} pi^{0},
and K^{0}_{S} h^{+} pi^{0}
(h^{+/-} denotes a charged pion or kaon),
without regard for the resonant substructure.
The only mode with a significant yield is
B --> K^{0} 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 f_{0}(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 K^{0}_{S} h^{+} pi^{-} and
K^{+} h^{-} pi^{0} 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 --> K ^{0} 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

cleoac@mail.lns.cornell.edu Last modified: Tue Jan 7 18:40:13 EST 2003