Model for Small neutrino masses at the TeV Scale

We propose a model for neutrino mass generation in wich no physics beyond a TeV is required. We extend the standard model by adding two charged singlet fields with lepton number two. Dirac neutrino masses mνD ≤ MeV are generated at the one loop level. Small left handed majorana neutrino masses can be generated via the seesaw mechanism with right handed neutrino masses MR are of order TeV scale. 1 Electronic address : [email protected] 2 Electronic address : [email protected] Solar and atmospheric neutrino oscillation experiments[1], give a strong evidence for the neutrino masses and mixings. In the minimal standard model, neutrinos are massless, due to the abscence of the right handed neutrino and the conservation of lepton number. Non zero Dirac neutrino masses can be obtained by adding, singlet fermions (right handed neutrinos) to the SM. However, in this case one needs to fine tune the Yukawa couplings to be ∼ 10−12, which is quite unnatural. An elegant and natural explanation of the smallness of the neutrino masses compared to the quarks and charged lepton masses is provided by the seesaw mechanism[2]. In this case the Majorana neutrino mass matrix is given by: