Observation and properties of the X(3872) decaying to J/psi pi+ pi- in p anti-p collitions at s**(1/2) = 1.96-TeV.

D0 Collaboration, The and Bertram, I. A. and Borissov, Guennadi and Ratoff, Peter N. and Sopczak, Andre and Davies, B. and Doidge, M. (2004) Observation and properties of the X(3872) decaying to J/psi pi+ pi- in p anti-p collitions at s**(1/2) = 1.96-TeV. Physical review letters, 93 (16). p. 162002. ISSN 1079-7114

Abstract

We report the observation of the X(3872) in the J/ψπ+π- channel, with J/ψ decaying to μ+μ-, in pp̅ collisions at sqrt[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.