Self-consistent Purcell factor and spontaneous topological transition in   hyperbolic metamaterials
  In this work we develop a self-consistent approach for calculation of the Purcell factor and Lamb shift in highly dispersive hyperbolic metamaterial accounting for the effective dipole frequency shift. Also we theoretically predict the possibility of spontaneous topological transition, which occurs not due to the external change of the system parameters but only due to the Lamb shift. 
Sergey Krasikov, Ivan Iorsh
physics.optics