Naturally Heavy Scalars in Supersymmetric Grand Unified Theories

TL;DR

This paper explores how multi-TeV scalar masses in supersymmetric grand unified theories can naturally evolve to the weak scale through renormalization group effects, reconciling heavy scalars with naturalness.

Contribution

It demonstrates a mechanism within GUTs where heavy scalar masses at high scales are driven to natural weak-scale values, especially highlighting the role of right-handed neutrinos.

Findings

Scalar masses can be increased to 4 TeV at the GUT scale without losing naturalness.

Right-handed neutrinos facilitate simple scenarios for heavy scalar masses.

Radiative evolution naturally aligns heavy scalars with weak-scale physics.

Abstract

The supersymmetric flavor, CP and Polonyi problems are hints that the fundamental scale of the soft supersymmetry breaking parameters may be above a TeV, in apparent conflict with naturalness. We consider the possibility that multi-TeV scalar masses are generated by Planck- or unification-scale physics, and find the conditions under which the masses of scalars with large Yukawa couplings are driven, radiatively and asymptotically, to the weak scale through renormalization group evolution. Light third generation scalars then satisfy naturalness, while first and second generation scalars remain heavy to satisfy experimental constraints. We find that this mechanism is beautifully realized in the context of grand unified theories. In particular, the existence of right-handed neutrinos plays an important role in allowing remarkably simple scenarios. For example, for SO(10) boundary conditions with the squared masses of Higgs scalars double those of sleptons and squarks, we find that the entire scalar mass scale may be increased to 4 TeV at the unification scale without sacrificing naturalness.