Triangle Seminars

Abstract:
We show how "generalised geometry", a class of extensions of conventional
differential geometry first introduced by Hitchin, gives a natural way of
formulating supergravity theories. The formulation unifies the bosonic
fields and symmetries and has a natural action of O(d,d) or the exceptional
groups E_d in d-dimensions. By introducing the analogue of the Levi-Civita
connection we find that full set of bosonic equations of motion reduce to
simply the vanishing of the generalised Ricci tensor. We show that the
connection also encodes the supersymmetry variations and fermionic equations
of motion.

This formalism also gives natural extensions of complex, symplectic and
other integrable structures, with implications for describing supersymmetric
string theory backgrounds.

Abstract:
Chiral anomalies have profound impact on the transport properties of relativistic fluids. They are closely related to the creation of currents by magnetic fields or vortices in the fluid via the so called Chiral Magnetic Conductivity and the Chiral Vortical Conductivity. Both can be computed by Kubo type formulae from special kinematic limits of two point functions of currents. I will review the calculation of these conductivites in a gas of free Weyl fermions and at strong coupling via a holographic model. A special and somewhat mysterious role is played by the mixed gauge-gravitational anomaly.