Observation and properties of the X(3872) decaying to J/ψπ⁺π^- in pp̅ collisions at √s=1.96 TeV

Abstract

We report the observation of the X(3872) in the J/ψ π⁺π^- channel, with J/ψ decaying to μ⁺μ^-, in pp̅ collisions at √s=1.96 TeV. Using approximately 230 pb^-1 of data collected with the Run II D0 detector, we observe 522±100 X(3872) candidates. The mass difference between the X(3872) state and the J/ψ is measured to be 774.9±3.1(stat)±3.0(syst)MeV/c². We have investigated the production and decay characteristics of the X(3872) and find them to be similar to those of the ψ(2S) state.