Effect of symmetrical frequency chirp on pair production*

By using Dirac–Heisenberg–Wigner formalism we study electron–positron pair production for linear, elliptic, nearly circular, and circular polarizations of electric fields with symmetrical frequency chirp, obtain momentum spectra yield. The difference results among polarized is obvious the small chirp. When chirp parameter increases, tend to exhibit multiphoton generation that characterized by multi-concentric ring structure. increase number density also remarkable compared case asymmetrical Note dynamically assisted Schwinger mechanism plays an important role enhanced in