Electroweak Supersymmetry with an Approximate U(1)_PQ

TL;DR

This paper proposes a supersymmetry framework incorporating an approximate Peccei-Quinn symmetry, predicting a modified MSSM spectrum with unique collider signatures and cosmological implications, largely independent of the PQ breaking details.

Contribution

It introduces a supersymmetry model with a dynamically predicted  parameter and a heavy pseudoscalar G, providing novel collider signatures and cosmological effects, independent of PQ breaking specifics.

Findings

Predicts a modified MSSM spectrum with an extra decay stage.

Compatible with experimental and astrophysical constraints.

Potential cosmological effects for light G, affecting N_{ u} during nucleosynthesis and CMB eras.

Abstract

A predictive framework for supersymmetry at the TeV scale is presented, which incorporates the Ciafaloni-Pomarol mechanism for the dynamical determination of the \mu parameter of the MSSM. It is replaced by (\lambda S), where S is a singlet field, and the axion becomes a heavy pseudoscalar, G, by adding a mass, m_G, by hand. The explicit breaking of Peccei-Quinn (PQ) symmetry is assumed to be sufficiently weak at the TeV scale that the only observable consequence is the mass m_G. Three models for the explicit PQ breaking are given; but the utility of this framework is that the predictions for all physics at the electroweak scale are independent of the particular model for PQ breaking. Our framework leads to a theory similar to the MSSM, except that \mu is predicted by the Ciafaloni-Pomarol relation, and there are light, weakly-coupled states in the spectrum. The production and cascade decay of superpartners at colliders occurs as in the MSSM, except that there is one extra stage of the cascade chain, with the next-to-LSP decaying to its "superpartner" and \tilde{s}, dramatically altering the collider signatures for supersymmetry. The framework is compatible with terrestrial experiments and astrophysical observations for a wide range of m_G and <s>. If G is as light as possible, 300 keV < m_G < 3 MeV, it can have interesting effects on the radiation energy density during the cosmological eras of nucleosynthesis and acoustic oscillation, leading to predictions for N_{\nu BBN} and N_{\nu CMB} different from 3.