Global gravitational anomalies and transport.

Marzo 30, 2017
De 3:00pm hasta 4:00pm

IFT Seminar Room/Red Room

Specialist level
Speaker: 
Subham Dutta Chowdhury
Institution: 
Indian Institute Of Science Bangalore, India.
Location&Place: 

IFT Seminar Room/Red Room

Abstract: 
We investigate the constraints imposed by global gravitational anomalies on parity odd induced transport coefficients in even dimensions for theories with chiral fermions, gravitinos and self dual tensors. The $\eta$- invariant for the large diffeomorphism corresponding to the $T$ transformation on a torus constraints the coefficients in the thermal effective action up to mod 2. We show that the result obtained for the parity odd transport for gravitinos using global anomaly matching is consistent with the direct perturbative calculation. In $d=6$ we see that the second Pontryagin class in the anomaly polynomial does not contribute to the $\eta$-invariant which provides a topological explanation of this observation in the `replacement rule'. We then perform a direct perturbative calculation for the contribution of the self dual tensor in $d=6$ to the parity odd transport coefficient using the Feynman rules proposed by Gaum\'{e} and Witten. The result for the transport coefficient agrees with that obtained using matching of global anomalies.