Inverse seesaw in supersymmetry

We study a mechanism where tiny neutrino masses arise only from radiative contribution in a supersymmetric model. Without tuning the Higgs vev or Yukawa coupling, the tree-level light neutrino mass is rotated away by introducing a new singlet neutrino sL that forms a Dirac mass term with the right-handed neutrino nR in each generation. Even with the U(1)Lep lepton number violation term as non-zero right-handed Majorana neutrino mass MRnRc¯nR, the lightest neutrino remains massless at tree level due to an approximate symmetry. Consequently, tiny neutrino masses then only arise from radiative contributions and the right-handed neutrino Majorana mass MR can be at O(keV) to give rise to the correct light neutrino mass at O(eV). Supersymmetry ensures that the Majorana neutrino masses MRnRc¯nR and MR⁎sLc¯sL are not generated simultaneously.