Nonlinear QED Effects

Quantum electrodynamics (QED) predictions have been very well tested in the high-energy, low-intensity regime using particle accelerators and spectroscopic experiments. In the presence of strong background fields, QED acquires some novel features  such as nonlinear QED effects.  The presence of virtual electron-positron pairs in the quantum vacuum leads to the nonlinear photon-photon scattering which have not been experimentally observed so far. Moreover, the existence of a strong enough electric field can also create pairs of charged particles from vacuum by Schwinger mechanism.
Such a strong fields can be provided by very high power lasers on the earth,  in the near vicinity of neutron stars, or even in the early stages of the universe's evolution.  In the astroparticle group, we are interested to explore the strong-field regime of QED whether in the ground based experiments or in the astrophysical medium. 

[1] Nonlinear QED effects in X-ray emission of pulsars, S. Shakeri, M. Haghighat and She-Sheng Xue, JCAP 1710 (2017) no.10, 014[arXiv:1704.04750]

[2] Polarization of a probe laser beam due to nonlinear QED effects,  Soroush Shakeri, Seyed Zafarollah Kalantari, She-Sheng Xue. 2017. 10 pp. Phys.Rev. A95 (2017) no.1, 012108.

[3] Schwinger Mechanism During Inflation, Soroush Shakeri, Mohammad Ali Gorji and Hassan Firouzjahi, Phys. Rev. D 99, 103525 (2019), [arXiv:1903.05310]