Is a Miracle-less WIMP Ruled Out?

TL;DR

This paper investigates a real electroweak triplet scalar as dark matter without relying on the standard freeze-out relic abundance, analyzing collider, direct, and indirect detection constraints to identify viable miracle-less WIMP scenarios.

Contribution

It provides a comprehensive analysis of bounds on electroweak triplet scalar dark matter in non-standard cosmological scenarios, highlighting the complementarity of different search methods.

Findings

LHC searches are effective for large or tiny mass splittings.

Direct detection constrains Higgs portal coupling, ineffective below 10^{-3}.

Indirect detection is viable for 100 GeV to TeV masses despite astrophysical uncertainties.

Abstract

We examine a real electroweak triplet scalar field as dark matter, abandoning the requirement that its relic abundance is determined through freeze out in a standard cosmological history (a situation which we refer to as a 'miracle-less WIMP'). We extract the bounds on such a particle from collider searches, searches for direct scattering with terrestrial targets, and searches for the indirect products of annihilation. Each type of search provides complementary information, and each is most effective in a different region of parameter space. LHC searches tend to be highly dependent on the mass of the SU(2) charged partner state, and are effective for very large or very tiny mass splitting between it and the neutral dark matter component. Direct searches are very effective at bounding the Higgs portal coupling, but ineffective once it falls below $\lambda_{\text{eff}} \lesssim 10^{-3}$. Indirect searches suffer from large astrophysical uncertainties due to the backgrounds and $J$-factors, but do provide key information for $\sim$ 100 GeV to TeV masses. Synthesizing the allowed parameter space, this example of WIMP dark matter remains viable, but only in miracle-less regimes.