Nonadiabatic quantum Vlasov equation in spinor QED

The nonadiabatic quantum Vlasov equation in spinor QED is derived, and its relation to the well-known adiabatic one is established by three methods. One is by an explicitly analytical expression, the second is by the Dirac equation in the V gauge, and the last is by introducing a turn-off electric field. Wherein what the first two of them are given is an instantaneous relation. Moreover, the time evolution of the distribution function for a specific momentum and the momentum distribution of created particle pairs after turning off the electric field are calculated and compared with those in scalar QED. It is found that both the oscillation periods of the distribution functions in spinor and scalar QED equal pi divided by the total energy of a particle after the electric field is turned off. The momentum distributions in spinor and scalar QED show a novel oscillation and out-of-phase behavior that cannot be explained by the Stokes phenomenon. These findings will further deepen our understanding of the quantum Vlasov equation and its application in vacuum pair production.
Comment: 12 pages, 6 figures