Scattering of a High-Intensity, Low-Frequency Electromagnetic Wave by an Unbound Electron

Polarization operator for plane-wave background fields

“…In conclusion, we can safely assume here that the background laser field can be treated as a given, classical background field (see also Refs. [66][67][68][69][70]).…”

Quantum Limitation to the Coherent Emission of Accelerated Charges

“…NSCS has been studied in the presence of a monochromatic plane wave [4,[8][9][10][11][12][13][14][15], of a pulsed plane wave [16][17][18][19][20][21][22][23][24][25][26], and of a space-timefocused laser beam [27] (see also [28][29][30][31]). In [4,[9][10][11][12][13][15][16][17][18][19][20][21][22][23][24][25] an incoming electron in a plane wave with a definite momentum was investigated, whereas in [14,26] NSCS by a localized electron wave packet was studied. In all these works, the radiation emitted by a single electron has been considered, such that coherence effects in the nonlinear emission by several electrons have never been investigated within strong-field QED.In this Letter we explore the novel features in the quantum radiation spectrum brought about by considering two-electron wave packets properly anti-symmetrized as an initial state.…”

Quantum Electrodynamics and the Correspondence Principle

“…of Fried and Eberly,12 the first one which included all orders. The propagator of (16), considered as a function of p, has a pole at p 2 =:m 2 +Am 2 ,…”

“…This drift velocity or incremental momentum, which exists classically before renormalization, has been cited as the cause of a frequency shift of Compton-scattered light. 12 This shift is very difficult to understand on a quantummechanical basis, 1 ' 17 but has been considered as inevit-able because of its classical nature and an uncritical application of the correspondence principle. If the renormalized momentum is taken as the quantum counterpart of the classical momentum, all these difficulties are resolved.…”