Neutrino Masses and Higgs Vacuum Stability

The Standard Model electroweak vacuum has been found to be metastable, with the true stable vacuum given by a large, phenomenologically unacceptable vacuum expectation value $\approx M_{P}$. Moreover, it may be unstable in an inflationary universe. Motivated by the necessity of physics beyond the Standard Model and to accommodate non-zero neutrino masses, we investigate vacuum stability within type-II seesaw and left-right symmetric models. Our analysis is performed by solving the renormalisation group equations, carefully taking into account the relevant threshold corrections. We demonstrate that a phenomenologically viable left-right symmetric model can be constructed by matching it with the SM at one-loop. In both models we demonstrate the existence of a large area of parameter space where the Higgs vacuum is absolutely stable.