  We consider an interacting homogeneous Bose gas at zero temperature in two
spatial dimensions. The properties of the system can be calculated as an
expansion in powers of g, where g is the coupling constant. We calculate the
ground state pressure and the ground state energy density to second order in
the quantum loop expansion. The renormalization group is used to sum up leading
and subleading logarithms from all orders in perturbation theory. In the dilute
limit, the renormalization group improved pressure and energy density are
essentially expansions in powers of the T-matrix.
