XIIème Ecole de Cosmologie
  15 - 20 septembre 2014 IESC, Cargèse
et leur impact dans l’étude des galaxies et la cosmologie

Observations and searches for candidates

Laboratoire d'Annecy-le-vieux de physique théorique (LAPTH) & Univ. de Savoie


  1. Zwicky’s legacy
    1. The historical discovery
    2. Galaxies and clusters of galaxies
    3. Cosmological observations
  2. The bestiary of dark matter species
    1. Following Charles Darwin
    2. Kaluza-Klein particles in extra-D theories
    3. The supersymmetric realm
    4. The WIMP miracle
  3. Particle astrophysics and the search for dark matter particles
    1. Direct detection experiments
    2. Indirect searches and cosmic rays
    3. The positron excess
  4.  Dark matter searches at the LHC


Large amounts of invisible matter in the universe have been discovered in 1933 when the Swiss astronomer Fritz Zwicky measured the velocity dispersion of individual galaxies inside the Coma cluster. Zwicky determined for the first time the dynamical mass of that system and obtained a value more than a hundred times larger than the visible counterpart inferred from the luminosity of galaxies. The astronomical dark matter puzzle originates from this measurement. Since then, it has been steadily confirmed by a series of refined observations, performed at very different scales, which I will review in the first chapter. The non-baryonic nature of dark matter is one of the most intriguing results and has been confirmed by the Planck satellite. In the second part, I will concentrate on the bestiary of candidates provided by the theoretical extensions of the standard model of particle physics. After a brief introduction to supersymmetry and Kaluza-Klein theories, I will pay particular attention to the WIMP miracle. Chapter 3 is devoted to the searches for dark matter candidates, with particular emphasis on weakly interacting massive species, dubbed WIMPs. Direct and indirect detections will be reviewed. An excess in the energy distribution of cosmic ray positrons has been discovered in 2008 above 10 GeV, raising the tremendous hope that WIMPs were not just a fantasy. Interpreting that excess as a smoking gun evidence for dark matter particles is very tempting. However, that possibility has by now fallen into disfavor on the basis of arguments which I will discuss. The final part of the lecture deals with the results collected during the first run of the large hadron collider (LHC) and the lack of direct evidence for physics beyond the standard model. I will discuss how this impacts on the models of dark matter and the WIMP properties.


  • For a review on the astronomical evidences for dark matter, see for instance
    • F. Zwicky, Helvetica Physica Acta 6, 110 (1933)
    • http://ned.ipac.caltech.edu/level5/Sept09/Einasto/frames.html
    • http://www.learner.org/courses/physics/unit/pdfs/unit10.pdf
  • For WIMP production in the early universe, see for instance
    • B. W. Lee and S. Weinberg, Phys. Rev. Lett. 39, 165 (1977)
    • P. Binetruy, G. Girardi and P. Salati, Nucl. Phys. B237, 285 (1984)
    • https://lapth.cnrs.fr/micromegas/
  • For direct and indirect searches for dark matter species, see for instance
    • http://arxiv.org/pdf/1403.4495.pdf
    • http://pos.sissa.it//archive/conferences/049/009/cargese_009.pdf
    • http://arxiv.org/pdf/1004.1092.pdf
  • For dark matter searches at the LHC, see for instance
    • http://www.mpi-hd.mpg.de/phenocond/pdf/collider-dm.pdf
    • http://moriond.in2p3.fr/J12/transparencies/14_Wednesday_am/malik.pdf
    • https://kicp-workshops.uchicago.edu/DM-LHC2013/presentations.php