Exploring elementary particles and their interactions is an age-old endeavour of humanity. With
the 27 km circumference Large Hadron Collider (LHC) at CERN and the monumental detectors
around it, scientists from all over the world have access to the most advanced tools to continue
this exploration. A major achievement was the experimental confirmation of the existence of the
Higgs boson particle in 2012, some 50 years after it had been predicted by Robert Brout, François
Englert, and Peter Higgs. Fundamental questions about the reality around us, however, remain,
such as, e.g., the nature of dark matter, the matter-antimatter asymmetry, the weakness of
gravity, and the unification of all forces. The Compact Muon Solenoid (CMS) detector, to which
the Flemish particle physics groups contributed in the design, construction, maintenance, and
operation since its conception in the 1990’s, allows to investigate and test many theoretical ideas
that are being proposed to answer these questions. This project is vital to pursue this
participation so that our groups can collect and analyse “Run 3” data and prepare the CMS
detector for the upgraded High-Luminosity LHC.