Subleading soft radiation during scattering of dressed states in QED

Abstract

We study soft photon emission during scattering of Faddeev-Kulish charged states in QED, at leading order in perturbation theory. The charged asymptotic particles are accompanied by clouds of an infinite number of soft photons of energy less than a characteristic infrared scale $E_d$. When the corresponding ``dressing'' functions are suitably corrected to subleading order in the soft momentum expansion, as advocated in recent work by Choi and Akhoury, we show explicitly that the emission of additional radiative soft photons with energy less than $E_d$ is completely suppressed. Moreover, the dressing renders the elastic amplitudes infrared-finite, order by order in perturbation theory, regulating the infrared divergences due to virtual soft photons, at the energy scale $E_d$. Therefore, the characteristic energy scale of the soft photons in the clouds provides an effective infrared cutoff, allowing for the formulation of an infrared finite S-matrix.

Revised version following peer review

References in corpus (18)

• Low's Subleading Soft Theorem as a Symmetry of QED
• Low-Energy Behavior of Gluons and Gravitons from Gauge Invariance
• On Loop Corrections to Subleading Soft Behavior of Gluons and Gravitons
• Loop Corrections to Soft Theorems in Gauge Theories and Gravity
• Infrared Divergences in QED, Revisited
• Shaving off Black Hole Soft Hair
• The SAGEX Review on Scattering Amplitudes
• Large Gauge Symmetries and Asymptotic States in QED
• Infrared quantum information
• Classical Sub-subleading Soft Photon and Soft Graviton Theorems in Four Spacetime Dimensions
• Dressed infrared quantum information
• On the Subleading-Soft Behaviour of QCD Amplitudes
• Dressed states from gauge invariance
• IR finite S-matrix by gauge invariant dressed states
• Gravitational soft theorem from emergent soft gauge symmetries
• Dress code for infrared safe scattering in QED
• Soft photon radiation and entanglement
• Soft Theorems from Boundary Terms in the Classical Point Particle Currents