Upper bound on $T_c$ in a strongly coupled electron-boson superconductor

Nikolay V. Gnezdilov, Rufus Boyack

Migdal-Eliashberg theory of boson-mediated superconductivity contains a $\sqrt{\hat{I}}»$ divergence in the critical temperature $T_c$ for strong electron-boson coupling $\hat{I}»$. In the conve…