Dynamic Jahn-Teller Effect and Colossal Magnetoresistance in $La_{1-x}A_xMnO_3$

A model for $La_{1-x}Sr_xMnO_3$ which incorporates the physics of dynamic Jahn-Teller and double-exchange effects is presented and solved via a dynamical mean field approximation. In an intermediate coupling regime the interplay of these two effects is found to reproduce the behavior of the resistivity and magnetic transition temperature observed in $La_{1-x} Sr_x MnO_3$.