Eur. Phys. J. C (2016) 76: 122
https://doi.org/10.1140/epjc/s10052-016-3981-4

Regular Article - Theoretical Physics

Electroweak vacuum stability and the seesaw mechanism revisited

¹ Theory Department, TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, Canada
² Department of Physics, Carleton University, 1125 Colonel By Drive, Ottawa, ON, K1S 5B6, Canada

^* e-mail: apuente@physics.carleton.ca

Received: 8 December 2015
Accepted: 25 February 2016
Published online: 4 March 2016

Abstract

We study the electroweak vacuum stability in Type I seesaw models for three generations of neutrinos in scenarios where the right-handed neutrinos have explicit bare mass terms in the Lagrangian and where these are dynamically generated through the mechanism of spontaneous symmetry breaking. To best highlight the difference of the two cases we concentrate on the absolute stability of the scalar potential. We observe that for the first scenario, the scale at which the scalar potential becomes unstable is lower from that within the standard model. In addition the Yukawa couplings are constrained such that . In the second scenario the electroweak stability can be improved in a large region of parameter space. However, we found that the scalar used to break the lepton number symmetry cannot be too light and have a large coupling to right-handed neutrinos in order for the seesaw mechanism to be a valid mechanism for neutrino mass generation. In this case we have .