Research Fellows Directory
Professor Christian Schwanenberger
University of Manchester
In our current understanding matter consists of molecules, which are formed by atoms, which in turn consist of a cloud of electrons orbiting a nucleus. The latter is made of protons and neutrons. While there is no hint of an electron substructure, protons and neutrons are made of two types of quarks. No substructure has yet been found for quarks and we call electrons and quarks elementary particles. Today we know several more elementary particles, for example there are six different types of quarks in total. One of those is called the top quark.
How could we find all that out? The principle is rather easy: we shoot particles onto each other and analyse the debris. This tells us what kind of particles exist and what kind of forces govern their interactions. The faster the initial particles are, the deeper we can probe matter and the heavier the particles we can discover. So we build colliders to accelerate the initial particles to the highest possible energies and use them as giant microscopes to get a detailed knowledge about the structure of matter.
I am interested in the top quark which is the heaviest known elementary particle. It was discovered 18 years ago. Although this particle appears to have no sub- structure and to be pointlike, it is as heavy as an atom of solid gold. Since it is so heavy, it cannot be assumed that its properties are simply those as predicted by the current theory. Therefore we want to measure these properties in detail and find out if the top quark behaves similarly to its five lighter siblings. But perhaps the top quark is exotic in some way, and will give us our first glimpse of physics beyond the current theory.
Currently all measurements I performed and supervised are in agreement with the current theory. Some results are still limited in precision so that top quark measurements will stay essential in understanding the mechanisms that govern our world from the tiniest particles to our universe.
Interests and expertise (Subject groups)