Spurious Poles in the Scattering of Electric and Magnetic Charges

TL;DR

This paper addresses the challenge of spurious poles in scattering amplitudes involving electric and magnetic charges, proposing a framework that ensures their cancellation and reveals novel electric-magnetic interaction effects.

Contribution

It demonstrates how confinement and parity conservation eliminate spurious poles in observable scattering amplitudes involving electric and magnetic charges.

Findings

Spurious poles cancel in physical amplitudes due to confinement and parity constraints.

Single photon production of magnetic particles by electric particles vanishes.

The work enables systematic study of dark electric-magnetic processes.

Abstract

Theories with both electric and magnetic charges ("mutually non-local" theories) have several major obstacles to calculating scattering amplitudes. Even when the interaction arises through the kinetic mixing of two, otherwise independent, U(1)'s, so that all low-energy interactions are perturbative, difficulties remain: using a self-dual, local formalism leads to spurious poles at any finite order in perturbation theory. Correct calculations must show how the spurious poles cancel in observable scattering amplitudes. Consistency requires that one type of charge is confined as a result of one of the U(1)'s being broken. Here we show how the constraints of confinement and parity conservation on observable processes manages to cancel the spurious poles in scattering and pair production amplitudes, paving the way for systematic studies of the experimental signatures of "dark" electric-magnetic processes. Along the way we demonstrate some novel effects in electric-magnetic interactions, including that the amplitude for single photon production of magnetic particles by electric particles vanishes.