Implications of Supersymmetry Breaking with a Little Hierarchy between Gauginos and Scalars

TL;DR

This paper analyzes a supersymmetric scenario with a little hierarchy between gauginos and scalars, where scalar masses are heavy around $m_{3/2}$ while anomaly mediation keeps gaugino masses light via $M_\lambda = \frac{\beta(g_\lambda)}{g_\lambda} m_{3/2}$. The resulting Wino-like LSP and decoupled scalars alleviate flavor/CP and proton-decay concerns and can preserve gauge and Yukawa unification, while staying compatible with Higgs mass constraints for viable $\tan\beta$. Collider phenomenology is dominated by gluino pair production, with searches reaching up to around $m_{\tilde{g}}\sim2$ TeV for substantial luminosity, and the LSP’s near-degeneracy with the charged state leads to soft decay products. Dark matter implications favor indirect detection through monochromatic gamma-ray lines from LSP annihilation, offering potential observational handles even when direct detection is suppressed.

Abstract

From a theoretical point of view it is not hard to imagine gaugino masses being much lighter than scalar masses. The dominant contributions to gaugino masses are then their anomaly-mediated values. Given current lower bounds on gauginos, which are near the W-mass scale, considering a little hierarchy between weak-scale gauginos and much heavier scalars requires suspending normal intuition on finetuning and naturalness of the Higgs potential. Nevertheless, tantalizing perks come from the hypothesis: lessened flavor and CP violation problems, more compatibility with gauge coupling unification and third generation Yukawa unification, suppressed dimension-five proton decay operators, and no problems satisfying the current Higgs mass constraint for any value of tan(beta) consistent with the top and bottom Yukawa couplings remaining finite up to the grand unified scale. The Tevatron has little chance of finding any evidence of this theory given current constraints. The LHC does well looking for pair production of gluinos which three-body decay into potentially spectacular final states. Dark matter relic abundance can be cosmologically interesting, but table-top experiments will not see LSPs scattering off nucleons. On the other hand, experiments looking for monochromatic photons from LSP annihilations in the galactic halo may find them.

Figures (1)

• Figure 1: Production cross-section of gluino pairs at the $\sqrt{s}=14\, {\rm TeV}$ LHC in the limit that all squarks are much heavier than the gluino. The final states associated with gluino pair production are at least four jets plus missing energy.