Synchrotron and annihilation channels for axion production in an external electromagnetic field

We consider axion formation processes in the synchrotron (e(-)-->e(-)a) and annihilation (e(-)e(+)-->a) channels in a constant crossed field Fmu nuFmu nu=F-mu nu*F-mu nu=0, which approximates constant fields of other configurations in the ultrarelativistic asymptotic limit. The probability and intensity of axion emission are obtained, and we analyze the energy and field asymptotics. A comparison with the characteristic neutrino channel e(-)-->e(-)nu<(nu)over bar> yields the constraints on the axion mass and the energy scale for Peccei-Quinn symmetry breaking. Possible astrophysical applications are discussed. (C) 1997 American Institute of Physics.