Angular momentum transfer in multiphoton pair production

TL;DR

This paper introduces a precise method to analyze angular momentum transfer in multiphoton pair production, revealing how topological charge relates to orbital angular momentum and demonstrating conservation laws in a circularly polarized electric field.

Contribution

The study presents a novel calculation method for momentum and phase distributions in pair production, clarifies the role of topological charge, and explores angular momentum conservation in a semiclassical framework.

Findings

Topological charge reflects orbital angular momentum of pairs.

Total angular momentum along z-axis is conserved.

Pairs with smaller OAM are produced more favorably.

Abstract

We propose a method to accurately calculate the momentum distributions and the phase distributions of the probability amplitude for both boson and fermion pair production in a spatially homogeneous and time-dependent electric field. Applying this method to multiphoton pair production in a circularly polarized electric field rotating around the $z$-axis, we clarify that the topological charge appearing in the phase distribution of the probability amplitude for pair production reflects the orbital angular momentum (OAM) of the produced pairs rather than that of individual particles. On this basis, we demonstrate that, within the semiclassical framework, the $z$-component of the total angular momentum of the field and the particles is conserved, whereas the conservation of total angular momentum cannot be verified. The results also reveal that the pair production is also constrained by $C$-parity conservation, and that pairs with smaller OAM are produced more favorably. These findings provide deeper insight into angular momentum transfer in pair production.