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Abstract

The process of nonlinear electron-positron pair production by an electron colliding with an arbitrary plane-wave electromagnetic field (nonlinear trident pair production) is studied analytically and numerically. Special emphasis is put on the properties of the transition amplitude. In fact, its original expression as resulting from applying the Wick's theorem turns out to be divergent. By utilizing a functional relation derived from gauge invariance, however, the amplitude is regularized and investigated in different regimes. In particular, the amplitude is divided into a two-step and a one-step contribution, depending on the scaling dependence on the laser pulse duration. The corresponding contributions to the positron angular distribution spectra and the resulting interference terms are studied numerically, emphasizing the possibility of measuring experimentally the one-step contribution.