Photon dispersion in a strong magnetic field with positronium formation: Theory

Positrinium atom is considered in a strong magnetic field in a vector-potential gauged asA _x =–By. The energy spectrum is obtained including its dependence on the centre-of-mass wave vector across the magnetic field. The pole-like contributions into the photon polarization operator coming from the positronium states are calculated and dispersion curves of joint photon-positronium states are obtained as trajectories of poles of the photon Green function in momentum space.When propagating in a strong magnetic field (B0.1B _cr 4×10¹² G) with curved lines of force, a photon is canalized along the magnetic field by adiabatically transforming into a bound electron-positron pair, which is a stronger effect than the analogous photon capture by transforming into an unbound pair at the edge of the continuum discussed previously by the authors. The effect of bound pair formation by-quanta in a strong magnetic field may be important near pulsars,-burst sources, powerful X-ray sources in close binary systems and other astronomical objects, recognized as magnetic neutron stars.