Anomalous interactions of holographic hadrons

Fundamental interactions of elementary particles are governed by various symmetries. Sometimes such symmetries are completely broken by quantum effects. These so-called quantum anomalies lead to effects that would be forbidden in classical physics. This project studies such processes for hadrons, which are short-lived bound states of quarks, the building blocks of protons and neutrons. The first and also most important example of a quantum anomaly has been the decay of neutral pions into two photons, which is normally excluded by symmetry considerations. A new method where the interactions of the fundamental particles are described by a holographic image of a higher-dimensional gravitational theory permits to evaluate these anomalous processes in domains where previous methods are insufficient. For example, one can study the scattering of light by light, for which such anomalous processes are particularly important, at energy scales relevant for quantum corrections to the magnetic moment of muons. The latter is currently studied with unprecedented precision in a new experiment at the Fermilab near Chicago. Other applications are anomalous production of hadrons in high-energy collider experiments such as the Large Hadron Collider LHC at the European particle physics laboratory CERN.