Soft Yukawa couplings in supersymmetric theories

TL;DR

This paper investigates how soft supersymmetry-breaking terms can radiatively generate fermion masses, affecting Higgs couplings, flavor physics, and magnetic moments, with implications for experimental tests and model constraints.

Contribution

It demonstrates that radiative fermion mass generation is viable within vacuum stability constraints and explores its effects on Higgs couplings, flavor observables, and supersymmetry violation signals.

Findings

Radiative fermion masses can be generated for first- and second-generation quarks and leptons.

Higgs-fermion couplings exhibit momentum-dependent form factors, enhancing low-momentum interactions.

A radiative muon mass can significantly contribute to the muon anomalous magnetic moment.

Abstract

The possibility of radiatively generated fermion masses arising from chiral flavor violation in soft supersymmetry-breaking terms is explored. Vacuum stability constraints are considered in various classes of models, and allow in principle all of the first- and second-generation quarks and leptons and the $b$-quark to obtain masses radiatively. Radiatively induced Higgs-fermion couplings have non-trivial momentum-dependent form factors, which at low momentum are enhanced with respect to the case of tree-level Yukawa couplings. These form factors may be probed by various sum rules and relations among Higgs boson decay widths and branching ratios to fermion final states. An apparent, large, hard violation of supersymmetry also results for Higgsino couplings. Mixing between left- and right-handed scalar superpartners is enhanced. A radiative muon mass is shown to lead to a relatively large and potentially measurable contribution to the muon anomalous magnetic moment. If the light-quark masses arise radiatively, the neutron electric dipole moment is suppressed by a natural phase alignment between the masses and dipole moment, and is below the current experimental bound. The possibility of neutrino masses arising from softly broken lepton number, and concomitant enhanced sneutrino-antisneutrino oscillations, is briefly discussed.