Strong-field QED features in the leptonic beam collision

We study the photon emission and pair production from the collision of dense and ultra-relativistic leptonic beams in the strong QED regime (χ_e ≫ 1 ). Analytical solutions to the yield of photons and pairs are obtained for low disruption regime, with beams having uniform transverse profiles. Analytical solutions for the low and high energy components of the photon spectrum are derived. Distinct spectral features are identified in these two components of the spectrum with distinct signatures associated with the strong QED regime. The yield and the spectrum features are also studied as a function of the bunch length (or disruption parameter). The analytical solutions are verified by both solving the numerical solution of the QED probability equations and via three dimensional particle-in-cell simulations with OSIRIS.