# 2008 Born medal and prize

Professor Hagen Kleinert

*Freie UniversitÃ¤t Berlin*

*For his outstanding theoretical contributions to a wide range of fields, including condensed matter physics, quantum field theory and statistical physics.*

Professor Kleinert, of the Institute of Theoretical Physics at the Free University of Berlin, is one of the most original and accomplished theoretical physicists in Germany. His many remarkable achievements include: the development of a method which allows one to convert a divergent strong-coupling expansion series into a convergent weak-coupling expansion providing the basis for a field theory at strong couplings; the discovery (with H Duru) of an exact path-integral solution for the hydrogen atom, the development of which has led to the solution of all path integrals for which the SchrÃ¶dinger equation is solvable; in liquid crystals, the first complete description (with K Maki) of an icosohedral phase; and the development of a quantum field theory which describes collective phenomena in superfluid Helium-3.

As well as his seminal contributions to diverse fields of physics, Professor Kleinert has written a number of influential textbooks which are universally known and widely used. In particular his book *Path Integrals in Quantum Mechanics, Statistics, Polymer Physics and Financial Markets* has become the standard work on path integrals and their applications.