Model Building from Asymptotic Safety with Higgs and Flavor Portals

TL;DR

This paper explores Standard Model extensions inspired by asymptotic safety, analyzing their renormalization group behavior, fixed points, and phenomenological implications, aiming for models that remain consistent up to the Planck scale.

Contribution

It introduces novel asymptotically safe Standard Model extensions with an enlarged scalar sector and detailed two-loop RG analysis, including phenomenology and experimental constraints.

Findings

Identification of UV fixed points for the models.

Models match measured gauge couplings and fermion masses.

Predictions for collider signatures and flavor violation processes.

Abstract

We perform a comprehensive search for Standard Model extensions inspired by asymptotic safety. Our models feature a singlet matrix scalar field, three generations of vector-like leptons, and direct links to the Higgs and flavor sectors via new Yukawa and portal couplings. A novel feature is that the enlarged scalar sector may spontaneously break lepton flavor universality. We provide a complete two-loop renormalization group analysis of the running gauge, Yukawa, and quartic couplings to find ultraviolet fixed points and the BSM critical surface of parameters, $i.e.$ the set of boundary conditions at the TeV scale for which models remain well-behaved and predictive up to the Planck scale without encountering Landau poles or instabilities. This includes templates for asymptotically safe Standard Model extensions which match the measured values of gauge couplings and the Higgs, top, and bottom masses. We further detail the phenomenology of our models covering production, decay, fermion mixing, anomalous magnetic moments, effects from scalar mixing and chiral enhancement, and constraints on model parameters from data. Signatures at proton-proton and lepton colliders such as lepton flavor violation and displaced vertices, and the prospect for electric dipole moments or charged lepton-flavor-violating type processes, are also indicated.