Absorption Probability of De Sitter Horizon for Massless Fields with Spin

TL;DR

This paper analytically calculates the absorption probabilities of massless fields with various spins in de Sitter space, revealing universal behavior for bosons and non-zero probabilities for fermions, advancing understanding of particle emission from cosmological horizons.

Contribution

It provides exact solutions for the radial equations of massless fields with spins 0, 1/2, 1, and 2 in de Sitter space and derives their absorption probabilities, including for fermions.

Findings

Absorption coefficients are universal for all bosonic fields, depending only on angular momentum.

Non-zero absorption probability for spin 1/2 fermions, contrasting previous results.

Analytic solutions expressed in hypergeometric functions for high-frequency regimes.

Abstract

The evaluation of the absorption coefficients are important for particle emission caused by Hawking radiation. In the case of cosmological particle emission from the event horizon in De Sitter space, it is known that the scalar wave functions are solved in terms of Legendre functions. For fields with higher spin, the solution has been examined with low frequency approximation. We shows that the radial equations of the fields with spin $0,1/2,1$ and $2$ can be solved analytically in terms of the hypergeometric functions. We calculate the absorption probability using asymptotic expansion for high frequency limit. It turns out that the absorption coefficients are universal to all bosonic fields; They depend only on the angular momentum and not spin. In the case of spin $1/2$ fermions, we can also find non-vanishing absorption probability in contrast to the previously known result.