Observation of psi(3686) -> p(p)over-bar phi
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Using a data sample of 4.48×108 ?(3686) events collected with the BESIII detector, we present a first observation of ?(3686)?pp ?, and we measure its branching fraction to be [6.06±0.38(stat)±0.48(syst)]×10-6. In contrast to the earlier discovery of a threshold enhancement in the pp-mass spectrum of the channel J/???pp, denoted as X(pp), we do not find a similar enhancement in ?(3686)?pp?. An upper limit of 1.82×10-7 at the 90% confidence level on the branching fraction of ?(3686)?X(pp)??pp? is obtained. © 2019 authors. Published by the American Physical Society.