SUSY without the Little Hierarchy

TL;DR

This paper introduces a gauge extension to the MSSM that reduces Higgs mass fine-tuning, predicts new particles including top partners and axion-like states, and achieves a heavier Higgs with milder tuning.

Contribution

It presents a novel gauge extension of the MSSM with double protection and non-decoupling D-terms, enabling a heavier Higgs and reduced fine-tuning.

Findings

Higgs mass can reach 135 GeV with less than 10% tuning.

Predicts top-partner fermions as light as 700 GeV.

Includes potential light axion-like and sterile neutrino states.

Abstract

We propose a simple gauge extension of the minimal supersymmetric standard model (MSSM), where the fine tuning in the Higgs mass parameters is highly reduced. The Higgs boson is insensitive to high energies because of supersymmetry and also because it is a pseudo-Goldstone boson of a global symmetry (referred to as double protection or super-little Higgs mechanism). A large shift in the Higgs quartic self coupling is obtained via a non-decoupling D-term coming from an extra gauge group, resulting in a Higgs that can be as heavy as 135 GeV with a tuning milder than 10%. With an appropriate choice of quantum numbers one can achieve that the additional quartic is generated without a corresponding shift in the Higgs mass, thus preserving the double protection of the Higgs. The model predicts the existence of several top-partner fermions one of which can be as light as 700 GeV, while the ordinary MSSM states could be as light as 400 GeV. In addition to many new particles in the multi-TeV range there would also be an axion-like state very weakly coupled to standard model (SM) matter which could be in the sub-GeV regime, and sterile neutrinos which could be light.