Spectral functions of correlated bosons in the dynamical mean-field theory

Abstract: With the development of optical lattices, a direct experimental realization of the quantum many-body theory models has become possible. One of the models realised with cold atomic lattices is the bosonic Hubbard model. It describes a genuine competition between the itinerant behavior of bosons, which leads to the formation of a Bose-Einstein condensate, and the localizing effect of the interaction between particles, which leads to a Mott insulator. The dynamical mean-field approximation to the bosonic Hubbard model gives a comprehensive theoretical description of correlated bosons in the superfluid and Mott-insulating phases. In the dynamical mean-field theory (DMFT), the lattice problem is replaced by an impurity coupled to dynamical self-consistent baths. This results in a set of DMFT equations that need to be solved self-consistently. I will present our results for the phase diagram, momentum distribution and spectral functions of correlated bosons obtained in a strong-coupling approximation to the DMFT equations.