Observation of a narrow charmonium-like state in exclusive B+ -> K+ pi+pi- J/psi decays
arXiv:hep-ex/0309032 · doi:10.1103/PhysRevLett.91.262001
Abstract
We report the observation of a narrow charmonium-like state produced in the exclusive decay process B+ -> K+ pi+pi- J/psi. This state, which decays into pi+pi- J/psi, has a mass of 3872.0+-0.6(stat)+-0.5(syst) MeV, a value that is very near the M_D + M_D* mass threshold. The results are based on an analysis of 152M B-Bbar events collected at the Upsilon(4S) resonance in the Belle detector at the KEKB collider. The statistical significance of the signal is in excess of 10 sigma.
10 pages 4 figures, submitted to Physical Review Letters