Interference effect in the photoproduction of electron-positron pairs by a nucleus in the field of two light waves

In the general relativistic case, the nonresonance photoproduction of electron-positron pairs by a nucleus in the field of two circularly-polarized light waves propagation in the same direction is theoretically investigated. It is shown that there are two considerably different kinematic regions: the noninterference region, where the basic multiphoton parameters are the Bunkin-Fedorov quantum parameters, and the interference region, where the interference effects play important role and the quantum interference parameters are treated as multiphoton parameters. The interference effect is found in the photoproduction of electron-positron pairs by a nucleus in the field of two light waves. This effect takes place in the interference region, is due to stimulated, correlated emission and absorption of photons of both waves, and is related to production of and electron-positron pair in the plane specified by the wave vector and incident photon momentum. For moderate fields, the cross sections for photoproduction of pairs by a nucleus in the indicated kinematic region are determined. It is shown that the partial cross section in the interference region with correlated emission (absorption) of equal numbers of photons of both waves can far exceed the corresponding cross section in any other geometry