# AG Kleinert

## Prof. Dr. Dr. h.c. mult. em. Hagen Kleinert

### E-Mail: h@klnrt.de

## Research topics

A number of physical systems are described in a systematic manner using quantum field theory. These fields represent fluctuating physical parameters, such as atomic position, electrical and magnetic fields, orientation of molecules, etc. The materials used can be in the solid state, fluids, liquid crystals, or atomic nuclei. Fields are also used to study the changing forms of the membranes formed by bilipids or detergents in systems involving biophysics and physical chemistry.

The fluctuation of these fields is most efficiently described using functional integrals, which provide a general mathematical framework for explaining the phenomena found in systems of this kind. This description leads to a universal understanding of all continuous phase transitions. It provides important insights into phase transitions such as the melting of crystals and how superconductivity emerges.

- This research group handles topics including:
- Theory of defect-induced phase transitions
- Quark and string physics
- Quantum mechanics
- Classical and statistical mechanics in spaces with bending and torsion
- Classical statistics
- Mathematical physics
- Field theory of critical phenomena
- Polymers
- Fluid characteristics
- Fluctuation effects in membranes
- Superfluid Helium 4 and Helium 3
- Superconductivity
- Quantum statistics
- Stochastic physics