Split Supersymmetry
G. F. Giudice, A. Romanino
TL;DR
The work reframes physics beyond the Standard Model by discarding naturalness as a binding constraint and instead leveraging gauge-coupling unification and dark matter. It analyzes Split Supersymmetry, where scalars are heavy but gauginos and Higgsino remain near the weak scale, and performs a two-loop unification study together with dark-matter relic-density considerations. By expressing unification in terms of beta-function coefficients $b_i$ and parameters $N_g$, $N_i$, and $n_H$, it identifies viable spectra that yield consistent $oldsymbol{\alpha_s(M_Z)}$, $oldsymbol{M_{ m GUT}}$, and perturbative $oldsymbol{\alpha_{ m GUT}}$, and computes related predictions for gaugino masses, Higgs mass, and neutralino relic abundance. The results point to testable collider signatures and delineate parameter regions where unification and dark-matter criteria are simultaneously satisfied.
Abstract
The naturalness criterion applied to the cosmological constant implies a new-physics threshold at 10^-3 eV. Either the naturalness criterion fails, or this threshold does not influence particle dynamics at higher energies. It has been suggested that the Higgs naturalness problem may follow the same fate. We investigate this possibility and, abandoning the hierarchy problem, we use unification and dark matter as the only guiding principles. The model recently proposed by Arkani-Hamed and Dimopoulos emerges as a very interesting option. We study it in detail, analysing its structure, and the conditions for obtaining unification and dark matter.