Features of electroweak symmetry breaking in five dimensional SUSY models

TL;DR

This paper investigates a five-dimensional supersymmetric model with extra dimensions, showing how modified renormalisation group equations can lead to lighter stops and reduced fine-tuning, but high-scale modifications are less effective.

Contribution

It demonstrates that RGE effects in 5D SUSY models can lower fine-tuning, while high-scale SUSY breaking pattern modifications are less impactful.

Findings

Light, maximally mixed stops are achievable with low SUSY breaking scale.

RGE effects significantly reduce fine-tuning in 5D SUSY models.

High-scale SUSY breaking modifications do not substantially improve naturalness.

Abstract

We explore the phenomenological predictions of a supersymmetric standard model, with a large extra dimension and unifying gauge couplings. The modified five dimensional renormalisation group equations make it possible to obtain light, maximally mixed stops, with a low scale of supersymmetry breaking and a low unification scale. This allows the fine-tuning to be lowered right down to the barrier coming directly from experimental lower limits on the stop masses. We also show that attempts at modifying the SUSY breaking pattern to obtain more natural soft terms at the high scale do not give the expected fine-tuning relaxation, and only RGE effects turn out to be effective in generating a lower fine-tuning.