Theoretical Particle Physics

Research interest focus on theoretical issues in and beyond the standard model of particle physics. The standard model describes the strong interactions of quarks and gluons (quantum chromodynamics, QCD) and also their electroweak interactions, as well as those of electrons and neutrinos. An important issue concerns the structure of hadrons, the bound states of quarks and gluons. Research activities range from descriptions of these bound states using light-front quantization in field theory (Ben Bakker) to studies of distribution and fragmentation functions needed in the description of high energy scattering processes, such as measured in accelerators around the world. Here our focus is on the role of transverse momenta of quarks and gluons, trying to establish the proper field theoretical description that consistently separates the long and short range physics. These studies also show new ways to probe new particles and interactions at a possible next layer, underlying the standard model  The symmetries of this layer may also show up in patterns of masses and mixings of neutrinos. The work on QCD is part of the ERC Advanced Grant project 'QCD at work' (QWORK). Studies presently focus on gluon distribution functions, their operator structure including gauge links and factorization issues and related topics in multiple parton interactions and soft collinear effective theories.  

The theoretical particle physics group collaborates within the National Institute for Subatomic Physics (Nikhef) with other university groups and theorists at the Nikhef Institute. Since 2013 the group is embedded in the Theory Group of the Nikhef Institute (


Contact: Prof. dr. Piet Mulders,