Impact of massive neutrinos on the Higgs self-coupling and electroweak vacuum stability

TL;DR

This paper investigates how right-handed neutrinos influence the Higgs self-coupling and vacuum stability, revealing that low-scale seesaw models can significantly alter the Standard Model predictions and potentially be tested at colliders.

Contribution

It demonstrates that low-scale seesaw models with right-handed neutrinos can impact Higgs vacuum stability and collider phenomenology, highlighting the importance of the Dirac Yukawa matrix.

Findings

Higgs mass window narrows with right-handed neutrinos.

Lower cutoff scale for vacuum stability in low-scale seesaw models.

Potential collider signatures of right-handed neutrinos.

Abstract

The presence of right-handed neutrinos in the type I seesaw mechanism may lead to significant corrections to the RG evolution of the Higgs self-coupling. Compared to the Standard Model case, the Higgs mass window can become narrower, and the cutoff scale become lower. Naively, these effects decrease with decreasing right-handed neutrino mass. However, we point out that the unknown Dirac Yukawa matrix may impact the vacuum stability constraints even in the low scale seesaw case not far away from the electroweak scale, hence much below the canonical seesaw scale of 10^15 GeV. This includes situations in which production of right-handed neutrinos at colliders is possible. We illustrate this within a particular parametrization of the Dirac Yukawas and with explicit low scale seesaw models. We also note the effect of massive neutrinos on the top quark Yukawa coupling, whose high energy value can be increased with respect to the Standard Model case.