Hadron Physics
Experimental Hadron Physics
Shortly after the Big Bang, the Universe consisted of nothing but the fundamental components of matter. Quarks and Gluons combined in a split second to form protons and neutrons. These compound particles are also called hadrons. Why don’t we observe single quarks and gluons? Why are the properties of hadrons not just the sum of the properties of their components? These are some of the main questions of hadron physics.
To track down these secrets of nature, we search for new combinations of the fundamental components of hadrons in experiments at the world’s large accelerator centres. The aim is to put all the pieces together and find a description for the observable world and its laws. In the process, we develop detectors at the forefront of modern technology which allows us to teach students in experimental physics at a high technological level.
Experimental Physics of Hadrons and Nuclei
One of the central questions in physics is the composition of matter. Especially considering hadrons, e.g. protons and neutrons, many phenomena remain unsolved. The theoretical description of the strong interaction, so-called quantum chromo dynamics (QCD), is in good agreement with most measurements. However, neither QCD nor effective theories or calculations in the framework of lattice QCD enable us to classify all currently known states and shed light on their inner structure.
Apart from the improvement of the theoretical description by theoretical physicists, it is also important to search for new predicted or unpredicted states. The precise measurement of known states is necessary to confirm or exclude the theoretical descriptions. Energy scan measurements allow for an exact identification of the mass and width of states while partial wave analysis enables us to extract further information like spin and parity.
To improve the data base, I collaborate with colleagues from all over the world to establish the PANDA experiment in Darmstadt and analyse data from the BESIII experiment in Beijing.
Theoretical Hadron and Particle Physics
We investigate the characteristics of strongly interacting matter. Our focus is to shed light upon the inner structure and dynamics of hadrons and nuclei which are made up of quarks and gluons – the fundamental elements of our matter. One particular challenge lies in the strength of the interaction between qaurks and gluons as described by quantum chromo dynamics which leads the common approximation methods to fail.
In order to investigate these strongly interacting hadronic systems, our chair uses in particular effective field theories that exploit certain symmetry properties of quantum chromo dynamics and enable a systematic and model independent approach to hadronic observables. These analytical methods are combined with numerical techniques like Monte Carlo simulations of hadrons on a grid to analyse the properties and dynamics of few-baryon systems and baryonic matter.
Further research areas comprise the dependence of quark mass on hadronic observables and its consequences for cosmology, electroweak processes and pion production on nucleons and light nuclei, quantum field theoretical treatment of spin 3/2 fields, isospin violating effects, hyperon-nucleon interaction and properties of hypernuclei as well as charmonium physics.
Theoretical Hadron Physics
The working group researches different fields of high-energy physics: from quantum chromo dynamics (QCD) as the theory of hadrons to models of the fundamental interactions. In our current research, we focus on the investigation of non-perturbative effects of QCD. Due to the mysterious property of colour confinement, QCD is one of the most captivating and dynamic theories ever known. There are numerous important non-perturbative phenomena in QCD. In order to understand them, we use various methods of quantum field theory.
We deal in particular with topological non-trivial field configurations like solitons and instantons. At the moment we consider the possibility that protons and neutrons constitute solitons of chiral fields in QCD. Such an idea of the basic components of the matter around us allows for the prediction of a new type of baryons – the Ө+ pentaquark.
Another fascinating topic is the application of tomographic methods to hadron physics. Apparently these methods can pave the way to generate three dimensional images of hadrons.