Joint HEP/CPM Seminar

Torsion, Hall Viscosity and Topological Insulators

Robert Leigh

University of Illinois at Urbana-Champaign

The effective action encoding elastic transport properties of topological insulators involves effective (non-dynamical) ‘gravitational’ variables. In the case of 2+1-dimensional time-reversal breaking topological insulators, the leading term in the action is a ‘Chern-Simons’ action involving the torsion. The coefficient of this term is the dissipationless Hall viscosity, a direct analogue of the Hall conductivity. In this talk, we review the calculation of the Hall viscosity in simple models, and discuss its interesting renormalization properties. The Hall viscosity has interesting implications, through anomaly inflow, for gapless edge modes.