Applications of gauge/gravity duality to strongly coupled systems (2/2)

by Dr Johanna Erdmenger (Max Planck-Institut fuer Physik)

Friday 26 Jun 2015, 14:30 → 16:00 Europe/Berlin

SR 2, building 2a (DESY Hamburg)

Based on string theory, gauge/gravity duality provides a new way to relate quantum field theories to gravity. In addition to its intrinsic interest, which consists of a new look at the relation between quantum physics and gravity, it has also significant practical applications. This is due to the fact that gauge/gravity duality maps strongly coupled quantum field theories to weakly coupled gravity theories, which are much more tractable. The purpose of this lecture is to introduce the subject to non-specialists and to present key application examples relevant to elementary particle and condensed matter physics. In the second lecture, we turn to application examples and explain how to introduce finite temperature and finite density into gauge/gravity duality. We introduce the calculation of spectral functions within gauge/gravity duality and explain how it replaces the weak-coupling quasiparticle picture in the strong coupling case. We present the famous example of the gauge/gravity duality result for the ratio of shear viscosity over entropy density and relate it to quantum critical behaviour. Finally we briefly discuss magnetic impurities and defects in gauge/gravity duality models. These involve a scale generation mechanism which may also be relevant for confining gauge theories.