Low-energy multi-photon scattering at tree-level and one-loop order in a homogeneous electromagnetic field

Fuente: arXiv
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Autores principales: Ahumada, Ivan, Copinger, Patrick, Edwards, James P.
Formato: Preprint
Publicado: 2025
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author Ahumada, Ivan
Copinger, Patrick
Edwards, James P.
author_facet Ahumada, Ivan
Copinger, Patrick
Edwards, James P.
contents We study low energy photons coupled to scalar and spinor matter in the presence of an arbitrary homogeneous electromagnetic field in a first-quantised (worldline) approach. Utilising a Fock-Schwinger gauge for both the scattering photons and homogeneous background, simple compact expressions are found for both the photon- and background-dressed effective action and propagator in scalar and spinor quantum electrodynamics. The low-energy limit allows identification of the coupling of the scattering photons as one of an effective homogeneous superposition of their field strengths, with amplitudes following from application of a suitable linearisation operator. To treat the linearisation, several techniques are employed, including a functional expansion based on the proper time formalism and worldline Green functions, linearised vertex operators under a worldline path integral, and a matrix expansion in the field strengths. We find, in particular, that a replacement rule converting scalar amplitudes to spinor amplitudes at one-loop order can, surprisingly, be extended to tree level amplitudes in the low energy limit. Finally, we discuss a novel worldline representation of the momentum space matter propagators, obtaining a suitable worldline Green function for this path integral satisfying homogeneous Dirichlet boundary conditions and momentum space vertex operators representing the scattering photons already in momentum space.
format Preprint
id arxiv_https___arxiv_org_abs_2507_22308
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Low-energy multi-photon scattering at tree-level and one-loop order in a homogeneous electromagnetic field
Ahumada, Ivan
Copinger, Patrick
Edwards, James P.
High Energy Physics - Theory
High Energy Physics - Phenomenology
We study low energy photons coupled to scalar and spinor matter in the presence of an arbitrary homogeneous electromagnetic field in a first-quantised (worldline) approach. Utilising a Fock-Schwinger gauge for both the scattering photons and homogeneous background, simple compact expressions are found for both the photon- and background-dressed effective action and propagator in scalar and spinor quantum electrodynamics. The low-energy limit allows identification of the coupling of the scattering photons as one of an effective homogeneous superposition of their field strengths, with amplitudes following from application of a suitable linearisation operator. To treat the linearisation, several techniques are employed, including a functional expansion based on the proper time formalism and worldline Green functions, linearised vertex operators under a worldline path integral, and a matrix expansion in the field strengths. We find, in particular, that a replacement rule converting scalar amplitudes to spinor amplitudes at one-loop order can, surprisingly, be extended to tree level amplitudes in the low energy limit. Finally, we discuss a novel worldline representation of the momentum space matter propagators, obtaining a suitable worldline Green function for this path integral satisfying homogeneous Dirichlet boundary conditions and momentum space vertex operators representing the scattering photons already in momentum space.
title Low-energy multi-photon scattering at tree-level and one-loop order in a homogeneous electromagnetic field
topic High Energy Physics - Theory
High Energy Physics - Phenomenology
url https://arxiv.org/abs/2507.22308