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Two oppositely charged particles created within a microscopic space-time region can be separated, accelerated over a much larger distance, and brought to a recollision by a laser field. Consequently, new reactions become feasible, where the energy absorbed by the particles is efficiently released. By investigating the laser-dressed polarization operator, we identify a new contribution describing high-energy recollisions experienced by an electron-positron pair generated by pure light when a gamma photon impinges on an intense, linearly polarized laser pulse. The energy absorbed in the recollision process over the macroscopic laser wavelength corresponds to a large number of laser photons and can be exploited to prime high-energy reactions. Thus, the recollision contribution to the polarization operator differs qualitatively and quantitatively from the well-known one, describing the annihilation of an electronpositron pair within the microscopic formation region. [ABSTRACT FROM AUTHOR]

Abstract: A detailed quantum-electrodynamic calculation of muon pair creation in laser-driven electron–positron collisions is presented. The colliding particles stem from a positronium atom exposed to a superintense laser wave of linear polarization, which allows for high luminosity. The threshold laser intensity of this high-energy reaction amounts to a few in the near-infrared frequency range. The muons produced form an ultrarelativistic, strongly collimated beam, which is explicable in terms of a classical simple-man''s model. Our results indicate the experimental feasibility of the process at high positronium densities in counterpropagating laser beams with the help of present-day technology. [Copyright &y& Elsevier]