Beyond standard model with neutrinos

ShorttitleOne of the outstanding problems in Particle Physics is the origin of neutrino masses and mixings. The neutrino mixing was observed atmospheric, solar , reactor and accelerator neutrino oscillation data which imply that they have a non zero mass. The simplest way to introduce a neutrino masses is to postulate a right-handed fermion , singlet under standard model gauge group that mixes with the standard model fermion via a Dirac mass term. However, to generate a a sub-electron volt neutrino mass , it is necessary to fine tune the corresponding Yukawa coupling to more than one part of a billion. We propose a model to generate a small neutrino masses at the TeV scale. In this model, the smallness of neutrino mass is not due to the largness of the right handed neutrino mass, but instead it is due to the smallness of the Dirac mass term which is induced at one loop level. We also discuss some ideas beyond four dimensions and the origin of matter anti-matter asymmetry in the universe