Study of the X(3872) and Y(4260) in B0-->J/psi pi+ pi- K0 and B-->J/psi pi+ pi- K- decays

TL;DR

This paper reports on the search for the X(3872) and Y(4260) particles in B meson decays, providing improved measurements of their properties and setting upper limits on certain decay modes using data from the BABAR experiment.

Contribution

It offers new measurements of the X(3872) production rates, a mass difference between decay modes, and the first upper limit on Y(4260) production in B decays.

Findings

Measured B decay branching fractions involving X(3872).

Observed a mass difference of 2.7 MeV/c2 for X(3872) in different decay modes.

Set an upper limit on Y(4260) production in B decays.

Abstract

We present results of a search for the X(3872) in B0-->X(3872)KS0,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 232x106 B[overline B] 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<BR(B0-->X(3872)K0,X-->J/psi pi+ pi-)<10.3x10-6 and the branching fraction BR(B-->X(3872)K-,X-->J/psi pi+ pi-)=(10.1+-2.5+-1.0)x10-6. We observe a (2.7+-1.3+-0.2)MeV/c2 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 BR(B-->Y(4260)K-,Y(4260)-->J/psi pi+ pi-)<2.9x10-5.