Supersoft Supersymmetry is Super-Safe

TL;DR

Supersoft supersymmetry models with large Dirac gluino masses can naturally evade current LHC jets plus missing energy searches, with suppressed production channels and finite scalar mass contributions, leading to weaker experimental bounds.

Contribution

This paper demonstrates that supersoft supersymmetry models with Dirac gauginos can naturally evade LHC constraints, providing a novel framework with suppressed colored sparticle production.

Findings

Current LHC bounds on squark masses are around 684-748 GeV.

Supersoft models suppress gluino and squark production channels.

Bounds on squark masses improve modestly with increased luminosity.

Abstract

We show that supersymmetric models with a large Dirac gluino mass can evade much of the jets plus missing energy searches at LHC. Dirac gaugino masses arise from "supersoft" operators that lead to finite one-loop suppressed contributions to the scalar masses. A little hierarchy between the Dirac gluino mass 5 - 10 times heavier than the squark masses is automatic and technically natural, in stark contrast to supersymmetric models with Majorana gaugino masses. At the LHC, colored sparticle production is suppressed not only by the absence of gluino pair (or associated) production, but also because several of the largest squark pair production channels are suppressed or absent. We recast the null results from the present jets plus missing energy searches at LHC for supersymmetry onto a supersoft supersymmetric simplified model (SSSM). Assuming a massless LSP, we find the strongest bounds are: 748 GeV from a 2j + MET search at ATLAS (4.7 fb^{-1}), and 684 GeV from a combined jets plus missing energy search using $\alpha_T$ at CMS (1.1 fb^{-1}). In the absence of a future observation, we estimate the bounds on the squark masses to improve only modestly with increased luminosity. We also briefly consider the further weakening in the bounds as the LSP mass is increased.