Axionphoton mixing in quantum field theory and vacuum energy
Abstract
We analyze axionphoton mixing in the framework of quantum field theory. The condensate structure of the vacuum for mixed fields induces corrections to the oscillation formulae and leads to nonzero energy of the vacuum for the component of the photon mixed with the axion. This energy generates a new effect of the vacuum polarization and it has the state equation of the cosmological constant, w =  1. This result holds for any homogeneous and isotropic curved spacetime, as well as for diagonal metrics. Numerical estimates of the corrections to the oscillation formulae are presented by considering the intensity of the magnetic field available in the laboratory. Moreover, we estimate the vacuum energy density induced by axionphoton mixing in the Minkowski spacetime. A value compatible with that of the energy density of the universe can be obtained for axions with a mass of (10^{3}10^{2}) eV in the presence of the strong magnetic fields that characterize astrophysical objects such as pulsars or neutron stars. In addition, a value of the energy density less than that of the Casimir effect is obtained for magnetic fields used in experiments such as PVLAS. The vacuum polarization induced by this energy could be detected in next experiments and it might provide an indirect proof of the existence of the axionphoton mixing.
The quantum field theory effects presented in this work may lead to new methods for studying axionlike particles.
 Publication:

Physics Letters B
 Pub Date:
 March 2019
 DOI:
 10.1016/j.physletb.2019.01.056
 arXiv:
 arXiv:1901.10473
 Bibcode:
 2019PhLB..790..427C
 Keywords:

 Axion photon mixing;
 Quantum field theory;
 Vacuum energy;
 High Energy Physics  Phenomenology;
 Astrophysics  High Energy Astrophysical Phenomena;
 High Energy Physics  Theory
 EPrint:
 8 pages, 2 figures. Accepted for publication on Phys. Lett. B