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

TL;DR

This paper explores the theoretical and phenomenological implications of a scenario where gaugino masses are much lighter than scalar masses, leading to benefits like reduced flavor violation and compatibility with unification, despite fine-tuning concerns.

Contribution

It proposes a little hierarchy model with anomaly-mediated gaugino masses, analyzing its advantages and experimental signatures compared to traditional models.

Findings

Less flavor and CP violation problems.

Compatibility with gauge coupling and Yukawa unification.

Potential signals in gamma-ray observations from dark matter annihilation.

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.