Unruh-DeWitt detector in $\textrm{AdS}_2$

TL;DR

This paper analyzes the response of an Unruh-DeWitt detector in two-dimensional anti-de Sitter space, exploring how boundary conditions affect particle detection and connecting results to Minkowski space limits.

Contribution

It provides explicit calculations of the detector response in AdS2 with various boundary conditions, revealing the role of the AdS scale as an infrared regulator.

Findings

Detector response depends on boundary conditions.

AdS limit recovers Minkowski space results.

AdS scale acts as an infrared regulator.

Abstract

We find the response function and the transition rate for an Unruh-DeWitt detector interacting with a conformal scalar field in global two-dimensional anti--de Sitter (AdS) spacetime with different boundary conditions at its conformal infinities. We calculate the particle energy spectrum as seen by subcritical accelerated detectors and discuss how it depends on the choice of the boundary condition. We show that, despite this nontrivial dependence on the boundary conditions, the limit when the AdS length scale tends to zero is well defined and leads to the well-known results of 1+1 Minkowski space. One can thus interpret the AdS energy scale as a natural regulator for the well-known infrared ambiguity of massless scalar fields in 1+1 Minkowski spacetime.