Dynamical GUT breaking and mu-term driven supersymmetry breaking
Ryuichiro Kitano
TL;DR
The paper addresses how to achieve dynamical GUT breaking with a realistic Higgs sector by identifying MSSM Higgs doublets as massless mesons of a strong gauge group, thereby resolving the doublet–triplet splitting problem. It systematically analyzes SU(Nc), Sp(Nc), and SO(Nc) models, finding viable vacua only in the Sp and SO branches, with the SO(9) construction developed in detail within the conformal window. A novel mechanism is explored in which a small μ-term drives metastable SUSY breaking that is mediated primarily by gauge interactions, yielding a gravitino LSP and a distinctive Higgs-sector soft term pattern; alternatively, cosmological-constant effects via Giudice–Masiero can generate μ-term and SUSY breaking connected to CC. The work links dynamical GUT breaking to low-energy phenomenology, offering testable predictions for the SUSY spectrum while highlighting cosmological and model-building challenges and avenues for extension to other GUT groups.
Abstract
Models for dynamical breaking of supersymmetric grand unified theories are presented. The doublet-triplet splitting problem is absent since the Higgs doublet superfields can be identified with the massless mesons of the strong gauge group whereas there are no massless states corresponding to the colored Higgs fields. Various strong gauge groups SU(Nc), Sp(Nc) and SO(Nc) are examined. In a model with SO(9) strong gauge group, adding the mu-term for the Higgs fields triggers to break supersymmetry in a meta-stable vacuum. The pattern of the supersymmetry breaking parameters is predicted to be the gauge-mediation type with modifications in the Higgs sector.