2 papers
physics.optics2026
A Reduced Action Integral for Photon-Photon Interactions in Vacuum
D. Ramsey, M. S. Formanek, J. P. Palastro
Electromagnetic waves propagating through vacuum can polarize virtual electron-positron pairs; this polarization, in turn, nonlinearly modifies their propagation. A semi-classical…
physics.plasm-ph2025
X-ray free-electron lasing in a flying-focus undulator
D. Ramsey, B. Malaca, T. T. Simpson +5
Laser-driven free-electron lasers (LDFELs) replace magnetostatic undulators with the electromagnetic fields of a laser pulse. Because the undulator period is half the wavelength of…