Hidden gauginos of an unbroken U(1): Cosmological constraints and phenomenological prospects

TL;DR

This paper explores supersymmetric models with hidden U(1) gauginos as dark matter, analyzing cosmological constraints, phenomenological implications, and potential collider signatures, especially considering kinetic mixing effects and their impact on early universe and gamma-ray observations.

Contribution

It provides a detailed analysis of the parameter space for hidden U(1) gauginos as dark matter, including cosmological constraints and collider prospects, with new insights into mixing parameter effects.

Findings

Scenarios with neutralino NLSP are excluded for typical mixing values.

Slepton NLSP scenarios are viable within specific mixing ranges.

Reheating temperature bounds are relaxed if gravitino is LSP and hidden gaugino is NLSP.

Abstract

We study supersymmetric scenarios where the dark matter is the gaugino of an unbroken hidden U(1) which interacts with the visible world only via a small kinetic mixing with the hypercharge. Strong constraints on the parameter space can be derived from avoiding overclosure of the Universe and from requiring successful Big Bang Nucleosynthesis and structure formation. We find that for typical values of the mixing parameter, scenarios with neutralino NLSP are excluded, while scenarios with slepton NLSP are allowed when the mixing parameter lies in the range chi~O(10^(-13) - 10^(-10)). We also show that if the gravitino is the LSP and the hidden U(1) gaugino the NLSP, the bounds on the reheating temperature from long lived charged MSSM relics can be considerably relaxed and we comment on the signatures of these scenarios at future colliders. Finally, we discuss the case of an anomalously small mixing, chi<<10^(-16), where the neutralino becomes a decaying dark matter candidate, and derive constraints from gamma ray experiments.