Self-Guiding of Electromagnetic Beams in Degenerate Relativistic   Electron-Positron Plasma
  The possibility of self-trapped propagation of electromagnetic beams in the fully degenerate relativistic electron-positron plasma has been studied applying Fluid-Maxwell model; it is shown that dynamics of such beams can be described by the generalized Nonlinear Schr\"odinger equation with specific type of saturating nonlinearity. Existence of radially symmetric localized solitary structures is demonstrated. It is found that stable solitary structures exist for the arbitrary level of degeneracy. 
V.I. Berezhiani, N.L. Shatashvili
physics.plasm-ph astro-ph.SR