ZhETF, Vol. 123,
No. 2,
p. 211 (February 2003)
(English translation  JETP,
Vol. 96, No. 2,
p. 180,
February 2003
available online at www.springer.com
)
THE VACUUMVACUUM AMPLITUDE AND BOGOLIUBOV COEFFICIENTS
Nikishov A.I.
Received: July 8, 2002
PACS: 11.55.m, 12.20.m
We consider the problem of fixing the phases of Bogoliubov coefficients in quantum electrodynamics such that the vacuumvacuum amplitude can be expressed through them. For a constant electric field and particles with spins 0 and 1/2, this is done starting from the definition of these coefficients. Using the symmetry between electric and magnetic fields, we extend the result to a constant electromagnetic field. It turns out that for a constant magnetic field, it is necessary to distinguish the in and outstates, although they differ only by a phase factor. For a spin1 particle with the gyromagnetic ratio g=2, this approach fails and we reconsider the problem using the propertime method.

