Research of the Top Quark sector at the LHC

Althought the top quark sector is accessible for dedicated research since its discovery in 1995, it remains a very rich and broad research domain with many unexplored aspects. Various event topologies of proton collisions in which top quarks appear are either described by the Standard Model or predicted in models beyond the Standard Model. The phenomenology of the top quark sector is strongly connected to the mechanism(s) of electroweak symmetry breaking and has in general an important interplay with supersymmetric models, models including a fourth chiral generation and models with extra spatial dimensions. The top quark sector therefore has a very rich and divers phenomenology which opens a variety of experimental challenges to be studied with the CMS experiment at the LHC.

Our team combines researchers from three Belgian universities working on both experimental and phenomenological aspects. All our members are part of the CMS Collaboration at CERN.

Staff members
  • Prof. Freya Blekman - Vrije Universiteit Brussel
  • Prof. Evelyne Daubie - Universite de Mons - CMS team leader UMons
  • Prof. Jorgen D'Hondt - Vrije Universiteit Brussel - CMS team leader VUB
  • Prof. Catherine Vander Velde - Universite Libre de Bruxelles - CMS team leader ULB
Post-doctoral researchers
  • Dr. Olivier Devroede - Vrije Universiteit Brussel
  • Dr. Rebeca Suarez - Vrije Universiteit Brussel
  • Dr. Petra Van Mulders - Vrije Universiteit Brussel

Pre-doctoral researchers
  • Stijn Blyweert - Vrije Universiteit Brussel
  • Thierry Caebergs - Universite de Mons
  • Gregory Hammad - Universite Libre de Bruxelles
  • Alexis Kalogeropoulos - Vrije Universiteit Brussel
  • Michael Maes - Vrije Universiteit Brussel
  • Annik Olbrechts - Vrije Universiteit Brussel
  • Gerrit Van Onsem - Vrije Universiteit Brussel
  • Ilaria Villella - Vrije Universiteit Brussel

Previous research members

  • Dr. Volker Adler (Universite Libre de Bruxelles and Vrije Universiteit Brussel) - now at the Universiteit Gent
  • Dr. Stephanie Beauceron (Vrije Universiteit Brussel) - now in Lyon (CNRS)
  • Dr. Eric Chabert (Universite Libre de Bruxelles) - now in Strasbourg (Maitre de Conference)
  • Jan Heyninck (Vrije Universiteit Brussel) - now Project Manager at Materialise
  • Steven Lowette (Vrije Universiteit Brussel) - now at the University of California (UCSB)
  • Joris Maes (Vrije Universiteit Brussel) - now at the University of Antwerp

PhD degrees and a link to the manuscript

  • Dr. Steven Lowette (Vrije Universiteit Brussel) - PhD in 2007 - won the CMS thesis Award 2008 - Thesis
  • Dr. Jan Heyninck (Vrije Universiteit Brussel) - PhD in 2008 - won the CMS thesis Award 2009 - Thesis
  • Dr. Petra Van Mulders (Vrije Universiteit Brussel) - phD in 2010 - Thesis
  • Dr. Joris Maes (Vrije Universiteit Brussel) - PhD in 2010 - Thesis
Organized conferences

Top 2010

3rd International Workshop on Top Quark Physics
Bruges, 31 May - 4 June 2010

The richness of the research of the top quark sector is translated into a variety of topics studied by our team. The important ones are summarized below.

  • Top quark properties: The study of the measurement of the mass of the top quark, and the interplay with the data-driven jet energy scale calibration techniques. The verification of the equality between the top and anti-top quark masses predicted by the CPT symmetry is a key element in our Quantum Field Theoretical description of particle physics.
  • Cross section and top quark event properties: The study of the measurement of the cross section of top quark pair production, together with the interplay of data-driven techniques to estimate the b-tagging efficiency and of the different backgrounds. The measurement of the CKM element Vtb can be combined with this study.
  • Top quark couplings: The Wtb interaction vertex has a rich and mainly unexplored phenomenology to be observed in the V-A form of the top quark decay. This study may provide insights in the mechanism of electroweak symmetry breaking or indirectly argument for physics beyond the Standard Model. Also the W helicity and the predicted spin correlations can be measured at the LHC.
  • Fourth generation quarks: The search for the fourth generation quarks (and possibly squarks) at the LHC is based on signatures similar to those of the third generation. The interpretation of these phenomena depends strongly on the base model considered, for example the Standard Model or models beyond the Standard Model like supersymmetric models. The high centre-of-mass energies obtained at the LHC provide a new window to study these phenomena.
  • The interplay of supersymmetry and top quarks: In the search for supersymmetric phenomena at the LHC, the Standard Model processes with top quarks are usually the dominating background. Also top quarks can appear in the cascade decays of supersymmetric particles. This motivates a dedicated study of supersymmetric phenomena in the top quark sector.

The research of our group is embedded in the Inter-university Institute for High Energies (IIHE) where the CMS group is also active in for example the research of High Energetic Electron Pairs (link) and a new phenomenology group has been created (link).

We receive support from the FWO, FNRS, IWT, FRIA and the IUAP Fundamental Interactions.

All our members can be contacted via email. For specific information about the team, the coordinates below can be used.

Prof. Freya Blekman
Vrije Universiteit Brussel
Pleinlaan 2
B-1050 Brussel
phone:      ++32-2-6293211
secr:         ++32-2-6293203
Prof. Evelyne Daubie
Universite de Mons
Av. Maistriau, 19     
B - 7000 Mons
+32 (0)65 373387
+32 (0)477 723202   
secr :     
+32 (0)65 373386
Prof. Jorgen D'Hondt
Vrije Universiteit Brussel
Pleinlaan 2
B-1050 Brussel
phone:      +32 (0)2 629 3483
mobile:     +32 (0)496 704865
secr:         +32 (0)2 629 3203

Prof. Catherine Vander Velde
Universite Libre de Bruxelles
Boulevard du Triomphe, CP230
B-1050 Bruxelles
phone:  +32 (0)2 629 3208
fax:       +32 (0)2 629 3816
secr:     +32 (0)2 629 3202