Sommerfeld enhancement of right-handed sneutrino dark matter

The relic abundance of the lightest right-handed sneutrino dark matter in supersymmetric B - L extension of the standard model is revisited. Through the exchange of light B - L Higgs bosons, we investigate the bound state of the attractive Yukawa potential and obtain a large non-perturbative Sommerfeld enhancement effect. We emphasize that with this effect the relic abundance of right-handed sneutrino will lie within the observational limits and the right-handed sneutrino will remain a viable dark matter up to a mass of order 1.5 TeV.