The e+e- decay partial width of the recently observed state, X(3872), is estimated using the ISR data collected at the center of mass energy 4.03 GeV in e+e- annihilation experiment by BES at BEPC. It is found that the product of the e+e- partial width and X(3872) --> pi+ pi- J/psi decay branching fraction is less than 10 eV at 90 % confidence level if the J(PC) of X(3872) is 1(--). Together with the potential models and other information, we conclude that X(3872) is very unlikely to be a vector state.
@article{arxiv.hep-ph/0310261,
title = {The upper limit of the e+e- partial width of X(3872)},
author = {C. Z. Yuan and X. H. Mo and P. Wang},
journal= {arXiv preprint arXiv:hep-ph/0310261},
year = {2008}
}