As a theoretical Particle Physics physicist, I try to predict the properties of certain particles as precisely as possible. By comparing with corresponding experiments, we aim to discover where the Standard Model has weaknesses. Many experimental results today are associated with very small uncertainties. Our goal is to keep pace with this in our theoretical predictions.

We are particularly concerned with the strong interaction, as it is the most complicated to calculate – we can no longer do this with paper and pencil. The strong interaction binds quarks together within the atomic nucleus and is mediated by gluons. To predict their dynamics, we need supercomputers and must simplify the real world. For this, we use lattice field theory.

In the first step, we limit ourselves to a finite section of reality: We consider a cube that must be large enough for bound states of quarks and gluons – such as pions, protons, and neutrons – to exist within it without their properties being noticeably affected by the cube not being infinitely large. Then, we place individual lattice points into the cube.

Now we simulate many different configurations of how the gluons interact with themselves and the quarks at the lattice points. Hundreds to thousands of such snapshots form an ensemble. In almost all projects in Mainz, we use the same set of 25 ensembles: It is, so to speak, our toolbox, and with it, we can, for example, calculate the anomalous magnetic moment of the muon.

Here, a new experimental value caused quite a stir last year, as the current theoretical value deviates significantly. With new, innovative lattice calculations, which have only become possible in the last few years, we aim to continuously refine our prediction. This can only be achieved within a large collaboration and makes research very exciting in these times.

Dr. Simon Kuberski has been a postdoctoral researcher in Prof. Dr. Hartmut Wittig’s group since October 2020. What fascinates him most about his research is how it is possible to describe a great deal of physics with just a few fundamental equations and parameters – at once so simple and yet so complex.