Absorption cross section in de Sitter space

TL;DR

This paper investigates the absorption cross section of a scalar field in three-dimensional de Sitter space, exploring its relation to the cosmological horizon and the dS/CFT correspondence.

Contribution

It provides a method to estimate the absorption cross section in de Sitter space and connects it to the dual CFT description, especially for low-energy and low-temperature regimes.

Findings

Low-energy s-wave absorption cross section equals the horizon area.

High-temperature limit reveals horizon-related information.

CFT-side computation supports the dS/CFT correspondence.

Abstract

We study the wave equation for a minimally coupled massive scalar in three-dimensional de Sitter space. We compute the absorption cross section to investigate its cosmological horizon in the southern diamond. Although the absorption cross section is not defined exactly, we can be determined it from the fact that the low-energy $s(j=0)$-wave absorption cross section for a massless scalar is given by the area of the cosmological horizon. On the other hand, the low-temperature limit of $j\not=0$-mode absorption cross section is useful for extracting information surrounding the cosmological horizon. Finally we mention a computation of the absorption cross section on the CFT-side using the dS/CFT correspondence.