Study of the X(3872) and Y(4260) in B-0 -> J/psi pi(+)pi K--(0) and B--> J/psi pi(+)pi K--(-) decays

We present results of a search for the X(3872) in B-0-> X(3872)K-S(0), X(3872) -> J/psi pi(+)pi(-), improved measurements of B- -> X(3872)K-, and a study of the J/psi pi(+)pi(-) mass region above the X(3872). We use 232 x 10(6) B (B) over bar pairs collected at the Upsilon(4S) resonance with the BABAR detector at the PEP-II e(+)e(-) asymmetric-energy storage rings. The results include the 90% confidence interval 1.34x10(-6) < B(B-0 -> X(3872)K-0, X -> J/psi pi(+)pi(-)) < 10.3 x 10(-6) and the branching fraction B(B- -> X(3872)K-, X -> J/psi pi(+)pi(-)) = (10.1 +/- 2.5 +/- 1.0) x 10(-6). We observe a (2.7 +/- 1.3 +/- 0.2)MeV/c(2) mass difference of the X(3872) produced in the two decay modes. Furthermore, we search for the Y(4260) in B decays and set the 95% C.L. upper limit B(B--> Y(4260)K-, Y(4260) -> J/psi pi(+)pi(-)) < 2.9 x 10(-5).