QLunch: Optimal Upper Bound for the Correlation Energy of the Mean-Field Fermi Gas

Speaker: Niels Benedikter from IST Austria

Title: Optimal Upper Bound for the Correlation Energy of the Mean-Field Fermi Gas

Abstract: While Hartree-Fock theory is well established as a fundamental approximation for interacting fermions, it has been unclear how to describe corrections due to many-body correlations. I explain how correlations can be described by an effective quadratic Hamiltonian obtained by bosonizing collective pair excitations. We then use an approximate Bogoliubov theory to construct a trial state with Gell-Mann-Brueckner-type energy. Our result justifies the random phase approximation in the mean-field scaling regime, for repulsive, regular interaction potentials.