Pair annihilation in laser pulses: optical vs. XFEL regimes

TL;DR

This paper explores pair annihilation within ultra-short laser pulses, highlighting the differences in emission signatures and cross sections between optical and XFEL regimes, with implications for clearer experimental detection.

Contribution

It presents a theoretical analysis of single-photon pair annihilation in laser pulses, emphasizing the enhanced cross section and clearer signals in XFEL regimes compared to optical beams.

Findings

Cross section for pair annihilation is significantly larger in XFEL regimes.

Single-photon emission has a distinct, uni-directional signature.

XFEL parameters enable more detectable signals than optical beams.

Abstract

We discuss the theory and phenomenology of pair annihilation, within an ultra-short laser pulse, to a single photon. The signature of this process is the uni-directional emission of single photons with a fixed energy. We show that the cross section is significantly larger than for two-photon pair annihilation in vacuum, with XFEL parameters admitting a much clearer signal than optical beams.