Humboldt-Universität zu Berlin - Mathematisch-Naturwissen­schaft­liche Fakultät - Experimentelle Elementarteilchenphysik

ATLAS - AG Berge

Atlas Wide

ATLAS is a multi-purpose detector for elementary particles at the Large Hadron Collider (LHC) at CERN. Using high-energy proton beams of up to 7 TeV, measurements of properties of the Standard Model of elementary particle physics and searches for New Physics beyond that model are performed. The ATLAS collaboration consists of about 3000 scientific authors from more than 35 different countries all over the world. David Berge’s ATLAS group located at Humboldt-University is especially involved in dark matter phenomenology and searches. We work in close cooperation with DESY Zeuthen and Priscilla Pani’s Young Investigator Group.

Research Topics

Dark Matter

Multiple astrophysical observations hint at the existence of dark matter [1-3]. One good candidate for this dark matter is an electrically neutral, massive (GeV to TeV) and weakly interacting particle, a so-called WIMP. Such new particles could be produced in the LHC proton-proton collisions in association with other particles [4 - 7] and produce a characteristic transverse momentum imbalanced signature (“missing energy”), due to the fact that the dark matter particles escape ATLAS undetected. In this group, we focus on the characteristic signature of mono-jets, which consists of an energetic jet of particles, created in the hadronization of a quark or a gluon and produced in association with dark matter (compare [8, 9]).

Extended Higgs Sector

Interactions between dark matter and Standard Model particles could be mediated by a new scalar or pseudo-scalar particle [10]. Existing experimental constraints on this scenario can be relaxed by extending the Higgs sector with a second Higgs doublet. Mixing of the mediator with the second Higgs doublet then allows for the mediator’s coupling to Standard Model particles [11]. We investigate the phenomenology of such a model comprising a second Higgs doublet and a pseudo-scalar mediator (2HDM+a model, [12, 13]) and its parameter space that can be covered in analyses of events comprising missing transverse energy and a jet.

Research References
  1. V. Trimble, “Existence and Nature of Dark Matter in the Universe,” Annual Review of Astronomy and Astrophysics 25 no. 1, (1987) 425–472.
  2. G. Bertone, D. Hooper, and J. Silk, “Particle dark matter: evidence, candidates and constraints,” Physics Reports 405 no. 5, (2005) 279 – 390.
  3. J. L. Feng, “Dark Matter Candidates from Particle Physics and Methods of Detection,” Annual Review of Astronomy and Astrophysics 48 no. 1, (2010) 495–545.
  4. ATLAS/CMS Dark Matter forum, “Dark Matter benchmark models for early LHC Run-2 Searches: Report of the ATLAS/CMS Dark Matter Forum,” Physics of the Dark Universe (2019) 100371.
  5. LHC DM WG, “Recommendations on presenting LHC searches for missing transverse energy signals using simplified s-channel models of dark matter,” Physics of the Dark Universe (2019) 100365.
  6. The ATLAS collaboration, “Constraints on mediator-based dark matter and scalar dark energy models using √s = 13 TeV pp collision data collected by the ATLAS detector,” Journal of High Energy Physics 2019 no. 5, (May, 2019) 142.
  7. Steven Lowette on behalf of the CMS collaboration, “Search for Dark Matter at CMS,” Nuclear and Particle Physics Proceedings 273-275 (2016) 503 – 508. 37th International Conference on High Energy Physics (ICHEP).
  8. The ATLAS collaboration, “Search for dark matter and other new phenomena in events with an energetic jet and large missing transverse momentum using the ATLAS detector,” Journal of High Energy Physics 2018 no. 1, (Jan, 2018) 126.
  9. X. Cid Vidal et al., “Beyond the Standard Model Physics at the HL-LHC and HE-LHC,” arXiv:1812.07831 [hep-ph].
  10. U. Haisch, P. Pani, and G. Polesello, “Determining the CP nature of spin-0 mediators in associated production of dark matter and tt pairs,” Journal of High Energy Physics 2017 no. 2, (Feb, 2017) 131.
  11. P. Pani and G. Polesello, “Dark matter production in association with a single top-quark at the LHC in a two-Higgs-doublet model with a pseudoscalar mediator,” Physics of the Dark Universe 21 (2018) 8 – 15.
  12. M. Bauer, U. Haisch, and F. Kahlhoefer, “Simplified dark matter models with two Higgs doublets: I. Pseudoscalar mediators,” Journal of High Energy Physics 2017 no. 5, (May, 2017) 138.
  13. LHC DM WG, “LHC Dark Matter Working Group: Next-generation spin-0 dark matter models,” Physics of the Dark Universe (2019) 100351.
Group members

Prof. Dr. David Berge

Silvia Alessandria

Postdoctoral research fellows

PhD students

Martin Habedank

Master students


List of theses written within the ATLAS group


List of publications of the ATLAS group




LHC Dark Matter Working Group