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Is a Miracle-less WIMP Ruled Out?

by Jason Arakawa, Tim M. P. Tait

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Submission summary

Authors (as registered SciPost users): Jason Arakawa · Tim Tait
Submission information
Preprint Link: scipost_202105_00018v1  (pdf)
Date accepted: 2021-07-05
Date submitted: 2021-05-14 00:45
Submitted by: Arakawa, Jason
Submitted to: SciPost Physics
Ontological classification
Academic field: Physics
  • High-Energy Physics - Phenomenology
Approaches: Theoretical, Phenomenological


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.

Published as SciPost Phys. 11, 019 (2021)

Reports on this Submission

Anonymous Report 1 on 2021-6-24 (Invited Report)

  • Cite as: Anonymous, Report on arXiv:scipost_202105_00018v1, delivered 2021-06-24, doi: 10.21468/SciPost.Report.3116


1) The paper studies motivated physics beyond the standard model

2) The indirect detection analysis is very detailed


1) The introduction of the higher-dimensional operator does not seem strongly motivated to be and it has a clear impact on the phenomenology


This paper studies a dark matter model where the candidate is a complex scalar transforming as a triplet under the weak isospin. The authors introduce the theoretical framework in section 2. There are three different classes of interactions: couplings with gauge bosons, quartic Higgs portal in the scalar potential, and the dimension 6 effective operator given in equation (6). The last one makes it possible to lift the degeneracy between neutral and charged states, which is only due to gauge boson loop corrections at the renormalizable level. The authors consider the usual bounds on weak scale dark matter: collider (section 3), direct detection (section 4), indirect detection (section 5). They ignore relic density constraints that would otherwise exclude the model, and this is justified by the fact that dark matter freeze-out takes place way earlier than BBN and modified cosmological histories altering the relic density prediction are allowed. A nice summary of this study can be found in figure 10 where all the experimental bounds are accounted for.

The paper reads very well and everything is explained in a clear way. I believe the results are interesting enough to deserve to appear in the literature and I am happy to recommend this paper for publication.

  • validity: high
  • significance: high
  • originality: ok
  • clarity: high
  • formatting: excellent
  • grammar: perfect

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