| With the development of laser technology, the theoretical and experimental studies of production of high-energy particles in ultra-intense laser pulse has aroused great concern, especially electron-positron pair production from vacuum in the presence of strong electric field has become an important topic. Photons lost energy in the process of interaction with other particles, in addition to the photoelectric effect, Compton effect, another effect is the electron-positron pair production. Pair is an excellent example of the electronic radiation converted to the electron's rest mass and kinetic energy.In this paper, we studied the electron-positron pair production in elliptically polarized laser field and calculated pair production rate approximately. In the first chapter, we briefly reviewed the basic concepts of quantum electrodynamics, the Dirac theory,the Schwinger effect and the WKB approximation method and its application. Secondly, on the basis of the theoretical knowledge in the first chapter, we obtained the Dirac Hamiltonian in the strong electric field, and used the WKB approximation to calculate the two-level transition amplitude. Then, we have approximately calculated electron-positron pair production probability for two cases of low frequency elliptically polarized strong field and high frequency elliptically polarized weak field. Calculating results showed that:in the elliptically polarized high-frequency weak laser field, the pair production rate gradually decreased as the eccentricity increases; However, in the case of low frequency strong elliptical polarized laser field, the electron-positron pair production rate was consistent with the results in the existence of a constant electric field. Finally, our results were compared with previous results have been reported in this area. By comparison, we found that the electron-positron pair production probability in the circularly polarized laser field is smaller than the linearly polarized one. |
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