ISSN - 15507998, Physical Review D - Particles, Fields, Gravitation and Cosmology, 2013, vol. 88, p. -
Observation of a structure at 1.84 GeV/c2 in the 3(π+π -) mass spectrum in J/ψ→γ3(π+π -) decays
With a sample of 225.3×106 J/ψ events taken with the BESIII detector, the decay J/ψ→γ3(π+π-) is analyzed. A structure at 1.84 GeV/c2 is observed in the 3(π+π -) invariant mass spectrum with a statistical significance of 7.6σ. The mass and width are measured to be M=1842.2±4.2-2.6+7.1 MeV/c2 and Γ=83±14±11 MeV. The product branching fraction is determined to be B(J/ψ→γX(1840))×B(X(1840) →3(π+π-))=(2.44±0.36-0.74+0.60) ×10-5. No η′ signals are observed in the 3(π+π-) invariant mass spectrum, and the upper limit of the branching fraction for the decay η′→3(π +π-) is set to be 3.1×10-5 at a 90% confidence level. © 2013 American Physical Society.