Field-induced interaction of a pseudoscalar particle with photon in a magnetized $e^{-}{e}^{+}$ plasma

The effective interaction of a pseudoscalar particle with photon in plasma with the presence of a constant uniform magnetic field is investigated. It is shown that under some physical conditions the effective coupling between pseudoscalar particle and photon does not depend on medium parameters and particles momentum. The probability of the familon decay into photon pair in a strongly magnetized degenerate ultrarelativistic plasma is calculated.