### Abstract

We present results from a study of X(3872) → ππJ/ψ decays produced via exclusive B → KX(3872) decays. We determine the mass to be M_{X(3872)}= (3871.85 ± 0.27(stat) ± 0.19(syst)) MeV, a 90% confidence level upper limit on the natural width of Γ_{X(3872)}< 1.2 MeV, the product branching fraction B(B^{+}→ K^{+}X(3872)) X B(X(3872) → π^{+}π^{-}J/ψ) = (8.63±0.82(stat)±0.52(syst)) × 10^{-6}, and a ratio of branching fractions B(B^{0}→ K^{0}X(3872))/B(B^{+}→ K^{+}X(3872)) = 0.50±0.14(stat) ±0.04(syst). The difference in mass between the X(3872) → π^{+}π^{-}J/ψ signals in B^{+}and B^{0}decays is ΔM_{X(3872)}= (-0.71 ± 0.96(stat) ± 0.19(syst)) MeV. A search for a charged partner of the X(3872) in the decays B¯^{0}→ K^{-}X^{+}or B^{+}→ K^{0}X^{+}, X^{+}→ π^{+}π^{0}J/ψ resulted in upper limits on the product branching fractions for these processes that are well below expectations for the case that the X(3872) is the neutral member of an isospin triplet. In addition, we examine possible J^{PC}quantum number assignments for the X(3872) based on comparisons of angular correlations between final state particles in X(3872) → π^{+}π^{-}J/ψ decays with simulated data for J^{PC}values of 1^{++}and 2^{-+}. We examine the influence of ρ-ω interference in the M(π^{+}π^{-}) spectrum. The analysis is based on a 711 fb^{-1}data sample that contains 772 × 10^{6}BB¯ meson pairs collected at the Γ(4S) resonance in the Belle detector at the KEKB e^{+}e^{-}collider.

Original language | English |
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Article number | 052004 |

Journal | Physical Review D - Particles, Fields, Gravitation and Cosmology |

Volume | 84 |

Issue number | 5 |

DOIs | |

Publication status | Published - 2011 Sep 7 |

### All Science Journal Classification (ASJC) codes

- Nuclear and High Energy Physics
- Physics and Astronomy (miscellaneous)

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## Cite this

^{+}π

^{-}J/ψ decays.

*Physical Review D - Particles, Fields, Gravitation and Cosmology*,

*84*(5), [052004]. https://doi.org/10.1103/PhysRevD.84.052004