Seminatural SUSY from $E_7$ Nonlinear Sigma Model

TL;DR

This paper proposes a new focus point supersymmetry scenario based on the $E_7$ nonlinear sigma model, where squarks and sleptons are pseudo Nambu-Goldstone bosons with radiatively generated masses, reducing fine-tuning in electroweak symmetry breaking.

Contribution

It introduces a novel SUSY breaking framework using the $E_7$ nonlinear sigma model, linking particle masses to Nambu-Goldstone bosons and achieving lower fine-tuning.

Findings

Fine-tuning measure reduced to 30-70 with specific mass ratio

Squarks and sleptons are pseudo Nambu-Goldstone bosons with radiative masses

Implications for LHC searches and dark matter detection

Abstract

We present a new focus point supersymemtry breaking scenario based on the supersymmetric $E_7$ non-linear sigma model. In this non-linear sigma model, squarks and sleptons are identified with (pseudo) Nambu-Goldstone bosons. Their masses are generated only radiatively through gauge and yukawa interactions, and they are much smaller than the gravitino and gaugino masses at a high energy scale. On the other hand, Higgs doublets belong to matter multiplets and hence may have unsuppressed supersymmetry-breaking soft masses. We consider their masses to be equal to the gravitino mass at the high energy scale, assuming the minimal Kahler potential for Higgs doublets. We show that the fine-tuning measure of the electroweak symmetry breaking scale is reduced significantly to $\Delta=30-70$, if the ratio of the gravitino mass to the gaugino mass is around $5/4$. Also, the prospects of the discovery/exclusion of supersymmetric particles at the Large Hadron Collider and dark matter direct detection experiments are discussed.