NMSSM+

TL;DR

The paper introduces NMSSM+, an improved scale-invariant supersymmetric model that reduces fine-tuning, solves the domain wall problem, and stabilizes the proton by adding extra matter from an E6 gauge group.

Contribution

It proposes NMSSM+, a novel extension of the NMSSM with additional matter and symmetries, addressing fine-tuning and domain wall issues simultaneously.

Findings

NMSSM+ further reduces fine-tuning compared to NMSSM.

The model resolves the domain wall problem via a discrete R-symmetry.

Extra matter includes heavy D-fermions from E6 representations.

Abstract

It is well known that the scale invariant NMSSM has lower fine-tuning than the MSSM, but suffers from the domain wall problem. We propose a new improved scale invariant version of the NMSSM, called the NMSSM+, which introduces extra matter in order to reduce even more the fine-tuning of the NMSSM. The NMSSM+ also provides a resolution of the domain wall problem of the NMSSM due to a discrete R-symmetry, which also stabilises the proton. The extra matter descends from an E6 gauge group and fills out three complete 27-dimensional representations at the TeV scale, as in the E6SSM. However the U(1)_N gauge group of the E6SSM is broken at a high energy scale leading to reduced fine-tuning. The extra matter of the NMSSM+ includes charge 1/3 colour triplet D-fermions which may be naturally heavier than the weak scale because they receive their mass from singlet field vacuum expectation values other than the one responsible for the weak scale effective {\mu} parameter.