An Improved Limit for Γ_{ee} of X(3872) and Γ_{ee} Measurement of ψ(3686)


Using the data sets taken at center-of-mass energies above 4 GeV by the BESIII detector at the BEPCII storage ring, we search for the reaction e⁺e⁻→ γ(ISR}X(3872) → γ{ISR}π⁺π⁻J/ψ via the Initial State Radiation technique. The production of a resonance with quantum numbers JPC=1⁺⁺ such as the X(3872) via single photon e+e- annihilation is forbidden, but is allowed by a next-to-leading order box diagram. We do not observe a significant signal of X(3872), and therefore give an upper limit for the electronic width times the branching fraction Γ{ee} ^{X(3872)} ℬ(X(3872) → π⁺π⁻J/ψ) < 0.13 eV at the 90% confidence level. This measurement improves upon existing limits by a factor of 46. Using the same final state, we also measure the electronic width of the ψ(3686) to be Γ {ee} ^{ψ(3686)} = 2213 ± 18{stat} ± 99{sys} eV. © 2015 The Authors.



Charmonium, X(3872) mesons, Ψ(3686) mesons, Atomic spectroscopy, Electron-positron interactions, Branching fractions (Nuclear physics), Particles (Nuclear physics)—Charm

National Key Basic Research Program of China (Contract no.2015CB856700); National Natural Science Foundation of China (NSFC) (Contract nos..11125525, 11235011, 11322544, 11335008, 11425524); Joint Large-Scale Scientific Facility Funds of the NSFC and CAS (contract nos. 11179007, U1232201, U1332201); CAS (contract nos. KJCX2-YW-N29, KJCX2-YW-N45); German Research Foundation DFG (contract no. CRC-1044); Seventh Framework Programme of the European Union under Marie Curie International Incoming Fellowship Grant (agreement no. 627240; Ministry of Development of Turkey (contract no. DPT2006K-120470); Russian Foundation for Basic Research (contract no. 14-07-91152); U.S. Department of Energy (contract nos. DE-FG02-04ER41291, DE-FG02-05ER41374, DE-FG02-94ER40823, DESC0010118); WCU Program of National Research Foundation of Korea (contract no. R32-2008-000-10155-0).


CC BY 4.0 (Attribution), ©2015 The Authors