Regular Article - Theoretical Physics
Gradient models of the axion–photon coupling
Kazan Federal University, Institute of Physics, Kremlevskaya str. 18, 420008, Kazan, Russia
* e-mail: Alexander.Balakin@ksu.ru
Revised: 6 January 2012
Published online: 15 February 2012
We establish an extended version of the Einstein–Maxwell-axion model by introducing into the Lagrangian cross-terms, which contain the gradient four-vector of the pseudoscalar (axion) field in convolution with the Maxwell tensor. The gradient model of the axion–photon coupling is applied to cosmology: we analyze the Bianchi-I type Universe with an initial magnetic field, electric field induced by the axion–photon interaction, cosmological constant and dark matter, which is described in terms of the pseudoscalar (axion) field. Analytical, qualitative and numerical results are presented in detail for two distinguished epochs: first, for the early Universe with magnetic field domination; second, for the stage of late-time accelerated expansion.
© Springer-Verlag / Società Italiana di Fisica, 2012