Journal of High Energy Physics

, 2016:16 | Cite as

Implications of unitarity and gauge invariance for simplified dark matter models

  • Felix KahlhoeferEmail author
  • Kai Schmidt-Hoberg
  • Thomas Schwetz
  • Stefan Vogl
Open Access
Regular Article - Theoretical Physics


We show that simplified models used to describe the interactions of dark matter with Standard Model particles do not in general respect gauge invariance and that perturbative unitarity may be violated in large regions of the parameter space. The modifications necessary to cure these inconsistencies may imply a much richer phenomenology and lead to stringent constraints on the model. We illustrate these observations by considering the simplified model of a fermionic dark matter particle and a vector mediator. Imposing gauge invariance then leads to strong constraints from dilepton resonance searches and electroweak precision tests. Furthermore, the new states required to restore perturbative unitarity can mix with Standard Model states and mediate interactions between the dark and the visible sector, leading to new experimental signatures such as invisible Higgs decays. The resulting constraints are typically stronger than the ‘classic’ constraints on DM simplified models such as monojet searches and make it difficult to avoid thermal overproduction of dark matter.


Beyond Standard Model Cosmology of Theories beyond the SM 


Open Access

This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited.


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Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (, which permits use, duplication, adaptation, distribution, and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.

Authors and Affiliations

  • Felix Kahlhoefer
    • 1
    Email author
  • Kai Schmidt-Hoberg
    • 1
  • Thomas Schwetz
    • 2
  • Stefan Vogl
    • 2
    • 3
  1. 1.DESYHamburgGermany
  2. 2.Institut für Kernphysik, Karlsruher Institut für Technologie (KIT)KarlsruheGermany
  3. 3.Oskar Klein Centre for Cosmoparticle Physics, Department of PhysicsStockholm UniversityStockholmSweden

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