U boson at the BES III detector

The O(MeV) spin-1 U boson has been proposed to mediate the interaction among electron-positron and O(MeV) dark matter, in order to account for the 511 keV γ-ray observation by SPI/INTEGRAL. In this paper the observability of such a kind of U boson at BESIII is investigated through the processes e+e-→Uγ and e+e-→J/Ψ→e+e-U. We find that BESIII and high luminosity B factories have a comparable capacity to detect such a U boson. If the U boson decays mainly into dark matter, i.e. invisibly, BESIII can measure the coupling between the U boson and an electron-positron pair geR (see text) down to O(10-5), and cover large parameter space which can account for 511 keV γ-ray observation. On the other hand, provided that U decays mainly into the electron-positron, BESIII can detect geR down to O(10-3), and it is hard to explore the 511 keV γ-ray measurement allowed parameter space due to the irreducible QED backgrounds