Alladi Ramakrishnan Hall

Gauge theories on black hole spacetimes

Karan Fernandes

CMI, Chennai

My talk will consider constrained field theories on fixed black
hole spacetimes, which may either be asymptotically flat or possess a
cosmological horizon. I will demonstrate that non-vanishing gauge
parameters at the horizons lead to additional contributions in the
constraints of gauge theories from these surfaces (unlike spacetimes with
spatial boundaries). By applying the Dirac-Bergmann formalism on the
Maxwell field, the Gauss law constraint will be shown to involve surface
contributions from the horizons. The physical implication of this result on
charges at the horizon will be discussed. Since our result follows from the
Gauss law constraint, it has further implications on the gauge fixed
theory. I will consider fixing null components of gauge fields at the
horizons in scalar electrodynamics, as an example of an interacting theory,
within the Hamiltonian BRST formalism. I will derive the surface terms in
the BRST invariant action which results from this choice. It will also be
shown that horizons provide surface corrections to the ghost number charge
and the electromagnetic dressing of gauge invariant fields. I will conclude
with an overview of these results and discuss some future directions.