Axion–photon mixing in quantum field theory and vacuum energy

Abstract

We analyze axion-photon 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 non-zero 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 space-time, 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 axion-photon mixing in the Minkowski space-time. 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 axion-photon mixing.The quantum field theory effects presented in this work may lead to new methods for studying axion-like particles.

Quantum field theory of axion-photon mixing and vacuum polarization

“…As shown in Ref. [41], the off-diagonal components of Ξ µν (x) are zero for a homogeneous and isotropic universe, as well as for diagonal metrics, thus the energy density and pressure are ρ = g 00 Ξ 00 , and p = −g jj Ξ jj (no summation on the index j is intended), respectively. Then, we obtain the state equation of the cosmological constant: p = −ρ , where…”

“…Finally, we note that the presence of a gas in the conversion region increases the oscillation rate because the gas induces the effective mass of photon m γ = c 2 ω P . However, the plasma presence reduces the value of |Υ k | 2 , which in any case remain detectable [41].…”

“…In this paper we report the results presented in Ref. [41], obtained by analyzing axion-photon mixing in the framework of quantum field theory (QFT). We present new oscillation formulae for the axion-photon system and demonstrate the presence of QFT vacuum polarization induced by the condensate structure of the vacuum for mixed particles.…”

Optical analog of particle production in gravitational fields

“…Indeed, as demonstrated by Capolupo et al [23], in the quantum field theoretical framework axions and photons exhibit considerable mixing, which is somewhat similar to the mixing and oscillations of the neutrino flavors. Following [23], let us consider either one of the waveguides shown in Fig.4(a,b), which is subjected to a DC magnetic field B0 directed along the y coordinate. For the guided photon propagation along the x direction, the photon polarizations decouple, and the axion-photon mixing matrix for the state of polarization parallel to B0 may be obtained as…”

Gravity, entanglement and CPT-symmetry violation in particle mixing

“…We have several examples of such phenomenon both in the bosonic and fermionic sectors. In the first sector we have mixing among axion-photon [4][5][6], ηη ′ [7], neutral kaons [8] and B meson [9]. In the second one we can find the neutrino flavor oscillations [10,11], the neutron-antineutron oscillations that could be observed in the next generation of experiments using slow neutrons with kinetic energies of a few meV [12], and the quark mixing [13].…”