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Résumé |
QED is considered one of the most precise theories tested experimentally. In
recent days, it is often used as a playground for more advanced QFTs. However, a
strong electromagnetic background coupled to particles can bring a new class of
strong-field effects [1], which depend on its strength and structure. In this
talk, I will focus on scattering processes in a so-called constant crossed field
(CCF) with perpendicular electric and magnetic components of equal magnitude. The
symmetry of a CCF allows for treating its coupling to charged particles exactly in
scattering amplitudes.
The loop corrections in a CCF are remarkably enhanced by a CCF. The field induces
finite contributions, which grow power-like with the field strength. The
extraordinary (for QED) consequence is the arising of a strong non-perturbativity
in the particle interaction in the high-field limit. This was initially
conjectured by Ritus and Narozhny based on 3-loop calculations [2], and we further
confirmed this to all orders by resumming the leading-type diagrams [3]. As the
perturbative expansion breaks down, these corrections manifest a new fully non-
perturbative regime of interaction.
It is anticipated that this regime is within the reach of the next-generation
acceleration or ultra-high-intensity laser facilities. However, clear predictions
of observable features are lacking due to the non-perturbative nature of the
calculations. In this talk, I will review our current efforts on this ground. Some
processes, such as corrections to non-linear Compton emission by energetic
electrons, could be deduced from the unitarity arguments. The Dyson-Schwinger
approach could be a direct way to formulate the consistent theory deeply in the
high field regime [4]. In the concussion, we will also outlook on how such non-
perturbativity could arise in richer theories beyond QED. |
