Observation of e(+)e(-) -> gamma X(3872) at BESIII
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CitationAblikim, M., Achasov, M. N., Ai, X.C., Albayrak, O., Ambrose, D. J., An, F. F. ... BESIII Collaboration. (2014). Observation of e(+)e(-) -> gamma X(3872) at BESIII. Physical Review Letters, 112 (9), 7p. http://dx.doi.org/10.1103/PhysRevLett.112.092001.
With data samples collected with the BESIII detector operating at the BEPCII storage ring at center-of-mass energies from 4.009 to 4.420 GeV, the process e(+)e(-) -> gamma X(3872) is observed for the first time with a statistical significance of 6.3 sigma. The measured mass of the X(3872) is (3871.9 +/- 0.7(stat) +/- 0.2(syst)) MeV/c(2), in agreement with previous measurements. Measurements of the product of the cross section sigma[e(+)e(-) -> gamma X(3872)] and the branching fraction B [X(3872) -> pi(+)pi(-)J/psi] at center-of-mass energies 4.009, 4.229, 4.260, and 4.360 GeV are reported. Our measurements are consistent with expectations for the radiative transition process Y(4260) -> gamma X(3872).