Research Papers in Physics and Astronomy


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Published by American Physical Society. Phys. Rev. Lett. VOLUME 93, NUMBER 16. Copyright © 2004 American Physical Society. Used by permission.


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 √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=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.

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