A.N. Rubtsov, Moscow State University
Dynamical Mean Field Theory (DMFT) successfully describes a number of phenomena in correlated materials, because it handles all local electronic correlations. Similarly, local bosonic correlations are supposed to be handled by so-called EDMFT approach. However, we argue that EDMFT does not describe a formation of collective bosonic modes by correlated electrons. We propose an approach called dual bosons that can be described as an extension of EDMFT. The method is based on change of variables in path integral and subsequent expansion in diagram series. Collective modes appear as due to summation of ladder diagrams in new variables. We expect that the developed technique will allow, for example, to take into account magnon correlations in Hubbard model, as well as to describe plasmons in correlated media.