Heat transfer from Ni–W tapes in liquid nitrogen at different orientations in the field of gravity

Extended axion electrodynamics: Anomalous dynamo-optical response induced by gravitational pp-waves

“…The presented above set of master equations of the axion electrodynamics in the pp-wave gravitational background (see (22)-(28)) is a coupled system of nonlinear equations; search for exact solution of this system is a sophisticated but very interesting problem. In this sense the exact solutions discussed in [23] relate to the case of absence of the dynamo-optic phenomena, nevertheless, that results let us expect the formulated dynamooptical problem to be solved in the nearest future with some special conditions for the coupling constants. Here we restrict our-selves by analysis of a truncated model, which, nevertheless, displays the main new feature: the anomalous character of the axion-photon coupling in the medium moving non-uniformly.…”

“…Master equations of the extended axion electrodynamics form the sub-set of the total system of equations of the Einstein -Maxwell -axion model (see, e.g., [17,23]); they can be obtained by variation of the action functional…”

“…Here U i is the macroscopic velocity four-vector; we use the Landau-Lifshitz definition of U i considering it as a time-like eigen-vector of the stress-energy tensor of the matter (see, e.g., [23] for details). The electric field fourvector, E i ≡ F ik U k , and the magnetic induction fourvector, B i ≡ F * ik U k , are, clearly, orthogonal to the velocity four-vector U i .…”

“…We assume that the electromagnetic and axion fields inherit the pp-wave symmetry of the gravitational background, thus, the unknown functions depend on u only: [23]).…”

“…In the papers [17][18][19][20][21][22][23] we considered extensions of the axion electrodynamics, keeping in mind that even if the axion field is initially constant, external gravitational and electromagnetic fields are able to activate frozen axionphoton couplings in course of evolution of the corresponding physical system. In particular, we considered a non-minimal axion-photon coupling activated by gravitational waves [17]; non-stationary optical activity and gradient-type models of the axion-photon coupling in a cosmological context [18,19]; fingerprints of dark matter axions in the terrestrial electric and magnetic field variations [20]; electromagnetic waves in an axion-active plasma [21,22]; axionically induced anomalous behavior of the electromagnetic response to the gravitational wave action [23].…”