Effective Field Theory Description of Hawking Radiation

TL;DR

This paper employs effective field theory techniques to analyze Hawking radiation from four-dimensional black holes, reproducing the trace anomaly and characterizing the quantum state without quantum hair.

Contribution

It demonstrates how to derive the trace anomaly and the Hawking flux using effective action methods, providing a novel approach to black hole radiation analysis.

Findings

Reproduces the trace anomaly using Riegert's action.

Identifies a unique quantum state analogous to the Unruh state.

Shows no quantum hair arises from the effective action.

Abstract

A study is made of Hawking radiation from four-dimensional black holes using effective field theory methods. The trace anomaly for the stress tensor in a general curved spacetime background is reproduced using Riegert's action. The semiclassical stress tensor is evaluated in a Schwarzschild background taking a time-independent limit for the quantum state. Imposing physical boundary conditions on an initial Cauchy surface leads to a unique state, analogous to the Unruh state with a vanishing ingoing flux and a finite outgoing flux. In particular, there is no sign of quantum hair arising from this nonlocal effective action.