Expanding the parameter space of natural supersymmetry

Abstract

SUSY/SUGRA models with naturalness defined via small µ are constrained due to experiment on the relic density and the experimental limits on the WIMP-proton cross-section and WIMP annihilation cross-section from indirect detection experiments. Specifically models with small µ where the neutralino is higgsino-like lead to dark matter relic density below the observed value. In several works this problem is overcome by assuming dark matter to be constituted of more than one component and the neutralino relic density deficit is made up from contributions from other components. In this work we propose that the dark matter consists of just one component, i.e., the lightest neutralino and the relic density of the higgsino-like neutralino receives contributions from the usual freeze-out mechanism along with contributions arising from the decay of hidden sector neutralinos. The model we propose is an extended MSSM model where the hidden sector is constituted of a U (1) X gauge sector along with matter charged under U (1) X which produce two neutralinos in the hidden sector. The U (1) X and the hypercharge U (1) Y of the MSSM have kinetic and Stueckelberg mass mixing where the mixings are ultraweak. In this case the hidden sector neutralinos have ultraweak interactions with the visible sector. Because of their ultraweak interactions the hidden sector neutralinos are not thermally produced and we assume their initial relic density to be negligible. However, they can be produced via interactions of MSSM particles in the early universe, and once produced they decay to the neutralino. For a range of mixings the decays occur before the BBN producing additional relic density for the neutralino. Models of this type are testable in dark matter direct and indirect detection experiments and at the high luminosity and high energy LHC. *

A multi-temperature universe can allow a sub-MeV dark photon dark matter

“…The relic densities of the dark photon and of the dark fermion arise in part from a freeze-in mechanism [35][36][37][38][39]. In general the visible sector and the dark sectors will have different temperatures [40][41][42][43][44][45] (a similar setup has been considered in ref.…”

Corrections to Yukawa couplings from higher dimensional operators in a natural SUSY SO(10) and HL-LHC implications

“…Note that the second lightest neutralino has the same mass as the lightest chargino. Points (less than 8 GeV) and require special treatment [56]. Point (h) is an example of a stop coannihilation scenario where the stop lies close in mass to the LSP while point (j) points to a stau coannihilation region.…”

Hidden sectors and a multi-temperature universe

“…The dark photons, however, are unstable and decay before BBN and do not contribute to the relic density. In the analysis we assume that the dark particles are produced by the freeze-in mechanism [34][35][36][37][38]. Here even with feeble couplings to the visible sector it is possible to generate D and D in sufficient amounts to saturate the dark matter relic density [7].…”