Mass operator of an axion in a crossed field

The dominant one-loop electron contribution to the mass operator of an axion in a crossed field in the asymptotic limits of the parameters q ²/m _e ² and is calculated. The corresponding electromagnetic mass of the axion is compared with the quantum-chromodynamic mass due to mixing with π. Expressions are derived for the probability of pair creation a→e ⁺ e ⁻, and the fundamental conclusion is reached that refractive effects are present in the propagation of an axion in an external electromagnetic field. Zh. éksp. Teor. Fiz. 113, 1558–1565 (May 1998)