Natural Scherk-Schwarz Theories of the Weak Scale

TL;DR

This paper investigates 5D natural supersymmetric theories broken by Scherk-Schwarz mechanism, demonstrating they can address hierarchy problem with minimal fine-tuning and exploring phenomenological implications and extensions.

Contribution

It introduces a class of 5D Scherk-Schwarz SUSY models that naturally solve traditional fine-tuning issues in 4D SUSY theories, with minimal tuning and novel phenomenology.

Findings

Achieving the Higgs mass requires additional model structure.

Fine-tuning remains below approximately 10%.

Exploration of three extensions: extra matter, U(1)' gauge group, NMSSM-like solution.

Abstract

Natural supersymmetric theories of the weak scale are under growing pressure given present LHC constraints, raising the question of whether untuned supersymmetric (SUSY) solutions to the hierarchy problem are possible. In this paper, we explore a class of 5-dimensional natural SUSY theories in which SUSY is broken by the Scherk-Schwarz mechanism. We pedagogically explain how Scherk-Schwarz elegantly solves the traditional problems of 4-dimensional SUSY theories (based on the MSSM and its many variants) that usually result in an unsettling level of fine-tuning. The minimal Scherk-Schwarz set up possesses novel phenomenology, which we briefly outline. We show that achieving the observed physical Higgs mass motivates extra structure that does not significantly affect the level of tuning (always better than $\sim 10\%$) and we explore three qualitatively different extensions: the addition of extra matter that couples to the Higgs, an extra $U(1)^\prime$ gauge group under which the Higgs is charged and an NMSSM-like solution to the Higgs mass problem.