Large $A_{t}$ Without the Desert

TL;DR

This paper demonstrates that in a 5D MSSM framework, a large enough A_t coupling can be generated at low energies through RGE evolution, enabling a 125.5 GeV Higgs mass with potentially observable light stops at the LHC.

Contribution

It shows how power law running in five dimensions can produce a large A_t coupling from a high unification scale, improving naturalness and collider prospects.

Findings

Large A_t can be generated at low energies via 5D RGE running.

Sub-TeV stops are possible, potentially observable at the LHC.

Models with split families can satisfy collider constraints while maintaining naturalness.

Abstract

Even if the unification and supersymmetry breaking scales are around $10^6$ to $10^{9}$ TeV, a large $A_t$ coupling may be entirely generated at low energies through RGE evolution in the 5D MSSM. Independent of the precise details of supersymmetry breaking, we take advantage of power law running in five dimensions and a compactification scale in the $10-10^3$ TeV range to show how the gluino mass may drive a large enough $A_t$ to achieve the required $125.5$ GeV Higgs mass. This also allows for sub-TeV stops, possibly observable at the LHC, and preserving GUT unification, thereby resulting in improved naturalness properties with respect to the four dimensional MSSM. The results apply also to models of "split families" in which the first and second generation matter fields are in the bulk and the third is on the boundary, which may assist in the generation of light stops whilst satisfying collider constraints on the first two generations of squarks.