Statut | Confirmé |
Série | RENC-THEO |
Domaines | cond-mat.str-el,hep-th |
Date | Jeudi 20 Juin 2019 |
Heure | 10:00 |
Institut | IHP |
Salle | Salle 314 |
Nom de l'orateur | Kapustin |
Prenom de l'orateur | Anton |
Addresse email de l'orateur | |
Institution de l'orateur | Caltech |
Titre | Thermal Hall conductance as a relative topological invariant, or detecting gravitational anomalies for lattice systems |
Résumé | It is well-known that zero-temperature Hall conductance of a 2d system can be interpreted both as a bulk transport coefficient and a U(1) anomaly for the edge modes. The former interpretation allows one to write down a simple formula for it (Kubo formula). The latter interpretation explains why Hall conductance is a topological invariant. In this talk I will explain the difficulties in extending these considerations to thermal Hall conductance and how they are overcome. I argue that thermal Hall conductance should be regarded as an exact 1-form on the parameter space rather than a function. Another observation is that anomalies of edge modes can be interpreted in physical terms as violations of F. Blochs theorem about the absence of currents in an equilibrium state. Combining these observations, I show that low-temperature thermal Hall conductance of a gapped 2d system is robust under arbitrary deformations which do not close the gap. |
Numéro de preprint arXiv | |
Commentaires | |
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