Spread Supersymmetry

TL;DR

Spread Supersymmetry addresses how a scanning SUSY-breaking scale $\tilde{m}$ can be compatible with environmental bounds on dark matter by introducing a large forbidden window between ${\rm TeV}$ and $T_R$; this yields two main classes of spectra, including TeV-scale LOSP/ LSP in Spread SUSY and the Environmental MSSM. The authors analyze two realizations with a Higgsino LSP and a Wino LSP, showing preserved gauge coupling unification, a SM-like Higgs in the 100--145 GeV range, and distinctive dark matter and collider signatures such as monochromatic photons, direct detection cross sections around $10^{-47}$ cm$^2$, and disappearing charged tracks. The framework links the DM composition to the LSP mass via multiverse priors and loop-suppressed mass generation, providing testable predictions for gamma-ray lines, direct and indirect DM searches, and future linear colliders while keeping the colored sector out of reach at the LHC. Overall, the work offers a plausible multiverse-based route to TeV-scale new physics with clear experimental handles that distinguish it from naturalness-based SUSY scenarios.

Abstract

In the multiverse the scale of SUSY breaking, \tilde{m} = F_X/M_*, may scan and environmental constraints on the dark matter density may exclude a large range of \tilde{m} from the reheating temperature after inflation down to values that yield a LSP mass of order a TeV. After selection effects, the distribution for \tilde{m} may prefer larger values. A single environmental constraint from dark matter can then lead to multi-component dark matter, including both axions and the LSP, giving a TeV-scale LSP lighter than the corresponding value for single-component LSP dark matter. If SUSY breaking is mediated to the SM sector at order X^* X, only squarks, sleptons and one Higgs doublet acquire masses of order \tilde{m}. The gravitino mass is lighter by a factor of M_*/M_Pl and the gaugino masses are suppressed by a further loop factor. This Spread SUSY spectrum has two versions; the Higgsino masses are generated in one from supergravity giving a wino LSP and in the other radiatively giving a Higgsino LSP. The environmental restriction on dark matter fixes the LSP mass to the TeV domain, so that the squark and slepton masses are order 10^3 TeV and 10^6 TeV in these two schemes. We study the spectrum, dark matter and collider signals of these two versions of Spread SUSY. The Higgs is SM-like and lighter than 145 GeV; monochromatic photons in cosmic rays arise from dark matter annihilations in the halo; exotic short charged tracks occur at the LHC, at least for the wino LSP; and there are the eventual possibilities of direct detection of dark matter and detailed exploration of the TeV-scale states at a future linear collider. Gauge coupling unification is as in minimal SUSY theories. If SUSY breaking is mediated at order X, a much less hierarchical spectrum results---similar to that of the MSSM, but with the superpartner masses 1--2 orders of magnitude larger than in natural theories.

Figures (5)

• Figure 1: Two versions of the Spread Supersymmetry spectrum, with the Higgsino LSP (left) and the wino LSP (right).
• Figure 2: A large window between $\sim {\rm TeV}$ and $\approx T_R$ for the LOSP mass, $m_{\rm LOSP}$, is forbidden since it overproduces dark matter, beyond the bound in Eq. (\ref{['eq:xi-bound']}).
• Figure 3: The masses of superpartners as a function of $\tilde{m}$, both on logarithmic scales, for the case where supersymmetry breaking is transmitted to the superpartners at order $X^\dagger X$ (left) and at order $X$ (right). The forbidden window of Section \ref{['sec:forb-window']} is indicated by the shaded areas.
• Figure 4: The Higgs mass prediction in Spread Supersymmetry with Higgsino LSP as a function of $\sin 2\beta$. (The corresponding values of $\tan\beta$ are also indicated at the top.) The solid red curve gives the Higgs mass prediction for $m_t = 173.2~{\rm GeV}$, while the dark-shaded band shows the uncertainty coming from the experimental error of $\delta m_t = \pm 0.9~{\rm GeV}$. The uncertainty from the superpartner mass scale $\tilde{m}$ is depicted by the light-shaded band, which corresponds to $10^7~{\rm GeV} < \tilde{m} < 10^9~{\rm GeV}$.
• Figure 5: Evolution of the three gauge couplings, $g_{1,2,3}$ (solid, blue) and the top Yukawa coupling (dashed, red) for $\tan\beta = 1$ in Spread Supersymmetry with Higgsino LSP. The hypercharge gauge coupling has $SU(5)$ normalization.