Introduction to Axion Photon Interaction in Particle Physics and Photon Dispersion in Magnetized Media

Symmetries, global or local, always play an important role in the conceptual aspects of physics be in broken or unbroken phase. Spontaneous breaking of the continuous symmetries always generates various excitations with varying mass spectra. Axion is one of that type, generated via spontaneous breaking of a global Chiral U(1) symmetry named after its discoverers, Peccei and Queen. This symmetry is usually denoted by U(1)PQ. To give a brief introduction to this particle and its originwe have to turn our attention to the development of the standard model of particle physics and its associated symmetries. The standard model of particle physics describes the strong, weak and electromagnetic interactions among elementary particles. The symmetry group for this model is, SUc(3)× SU(2)×U(1). The strong interaction ( Quantum Chromo Dynamics (QCD)) part of the Lagrangian has SU(3) color symmetry and it is given by,