A non-vanishing neutrino mass and the strong CP problem: A new solution from the perspective of the EW-$\nu_R$ model

Abstract

The EW-$\nu_R$ model was constructed to provide a scenario in which right-handed neutrinos are non-sterile and have masses proportional to the electroweak scale, providing an opportunity to test the seesaw mechanism at the LHC. What was hidden in the model until recently is the chiral symmetry which helps solve the strong CP problem by using it to rotate $\theta_{QCD}$ to zero. It turns out the contribution from the electroweak sector to the effective $\bar{\theta}$ is proportional to the light neutrino masses and is naturally small, satisfying the constraint coming from the present absence of the neutron electric dipole moment, and without the need for an axion. Talk presented at the APS Division of Particles and Fields Meeting (DPF 2017), July 31-August 4, 2017, Fermilab. C170731