Abstract
We consider scattering of a photon on a short intense laser pulse at high energy. We argue that for ultra-short laser pulses the interaction is coherent over the entire length of the pulse. At low pulse intensity I the total cross section for electron–positron pair production is proportional to I. However, at pulse intensities higher than the characteristic value Is, the total cross section saturates – it becomes proportional to the logarithm of intensity. This non-linear effect is due to multi-photon interactions. We derive the total cross section for pair production at high energies by resuming the multi-photon amplitudes to all orders in intensity. We calculate the saturation intensity Is and show that it is significantly lower than the Schwinger's critical value. We discuss possible experimental tests.
Highlights
With advent of very intense laser beams, experimental study of the non-linear Quantum Electrodynamics in photon–photon interactions is becoming feasible
We argue that for ultrashort laser pulses the interaction is coherent over the entire length of the pulse
As noted in the Introduction, from the point of view of a high energy photon interacting with the ultra-short laser pulse, the later can be considered as a neutral medium characterized by a certain number density ρ
Summary
With advent of very intense laser beams, experimental study of the non-linear Quantum Electrodynamics in photon–photon interactions is becoming feasible. In the leading order in the perturbation theory, photon–photon scattering is an inelastic process in which photons annihilate into the electron–positron pair [9] Since this process is mediated by a fermion, the total cross section at high energies decreases with energy as σtot ∼ α2/s. As I recently demonstrated [22], multiple scattering of e−e+ pair in a very intense laser pulse produces strong non-linear effect on the pairproduction cross section. The main goal of this Letter is to present a detailed derivation and study the properties of the total cross section for γ interaction at high energies including the multiple scattering effect to all orders in the perturbation theory..
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