May 11, 2016

Standard Model of Particle Physics

In particle physics we study the fundamental constituents of matter and their interactions. During the last century a theoretical quantum theory was developed, known as the Standard Model. This model incorporates a unifying description for electromagnetism, the weak nuclear force and the strong nuclear force. Attempts to include the final remaining force, gravity, are ongoing but remain untested.

Although the Standard Model provides a consistent description there are reasons to believe that it cannot be a complete or fundamental theory:

Experimental particle physics tests the Standard Model and looks for possible deviations occuring in nature. Although some hints for deviations are reported no decisive observations have been made to date. My research is carried out at the LHCb Experiment at CERN.


In B-physics the interactions of particles containing b-quarks are studied: the B-hadrons. Due to the fact b-quark is a heavy quark of the third generation, B-hadrons can be used for quantitative comparisons between theory and experiments. The research focusses on two main topics:

The research in the Netherlands is carried out by the Nikhef B-physics department .

The Cosmic Matter - Antimatter Asymmetry

Example image - aligned to the right From the observations of the cosmic microwave background radiation the initial matter - antimatter asymmetrie (before the annihilation of all antimatter) is believed to be 10^-9. Andrei Sacharov has formulated three general conditions that are required to explain the observed matter - antimatter asymmetry:

Although the electroweak phase transition of the universe according to the Standard Model interactions includes all three conditions it is believed that the amount of matter dominance cannot be explained in this way. For this reason the LHCb experiment searches for new sources of CP violating interactions between elementary particles.

Rare B-Decays

Another method to search for new particles and interactions is to look for B-meson decay processes that are not allowed, or strongly suppressed, in the Standard Model. If additional particles or forces carriers exist such decays could occur more frequently and have characteristic features with signatures for these new particles. LHCb searches for such events.