Gauge hierarchy from electroweak vacuum metastability

Khoury, Justin und Steingasser, Thomas (2022): Gauge hierarchy from electroweak vacuum metastability. In: Physical Review D, Bd. 105, Nr. 5, 55031

Abstract

We consider the possibility that the gauge hierarchy is a byproduct of the metastability of the electroweak vacuum, i.e., that whatever mechanism is responsible for the latter also sets the running Higgs mass to a value smaller than its natural value by many orders of magnitude. We find that the metastability of the electroweak vacuum, together with the requirement that such a nontrivial vacuum exists, requires the Higgs mass to be smaller than the instability scale by around 1 order of magnitude. While this bound is quite weak in the Standard Model (SM), as the instability scale is similar to 10(11) GeV, simple and well-motivated extensions of the SM significantly tighten the bound by lowering the instability scale. We first consider the effect of right-handed neutrinos in the vMSM with approximate B - (L) over tilde symmetry, which allows for masses of order TeV for the right-handed neutrinos and O(1) Yukawa couplings. We find that right-handed neutrinos cannot by themselves fully explain the gauge hierarchy, as the tightest upper bound compatible with current experimental constraints is similar to 10(8) GeV. As we demonstrate on the example of the minimal SU(4)/Sp(4) composite Higgs model, this bound can be lowered significantly through the interplay of the neutrinos and a dimension-six operator. In this scenario, the bound can be brought down considerably, with the smallest value accessible by our perturbative treatment being of order similar or equal to 10 TeV, and consistently several orders of magnitude below its natural value. While this is insufficient to fully solve the gauge hierarchy problem, our results imply that, assuming the SM symmetry-breaking pattern, small running Higgs masses are a universal property of theories giving rise to metastability, suggesting a common origin of the two underlying fine-tunings and providing a strong constraint on any attempt to explain metastability.

• Dokumententyp: Zeitschriftenartikel
• Fakultät: Physik
• Themengebiete: 500 Naturwissenschaften und Mathematik > 530 Physik
• ISSN: 2470-0010
• Sprache: Englisch