The semileptonic baryonic decay Ds+→pp¯e+νe

The decay Ds+→pp¯e+νe with a proton-antiproton pair in the final state is unique in the sense that it is the only semileptonic baryonic decay which is physically allowed in the charmed meson sector. Its measurement will test our basic knowledge on semileptonic Ds+ decays and the low-energy pp¯ interactions. Taking into account the major intermediate state contributions from η,η′,f0(980) and X(1835), we find that its branching fraction is at the level of 10−9∼10−8. The location and the nature of X(1835) state are crucial for the precise determination of the branching fraction. We wish to trigger a new round of a careful study with the upcoming more data in BESIII as well as the future super tau-charm factory.