  Exciton condensation in an electron-hole bilayer system of monolayer
transition metal dichalcogenides is analyzed at three different levels of
theory to account for screening and quasiparticle renormalization. The large
effective masses of the transition metal dichalcogenides place them in a strong
coupling regime. In this regime, mean field (MF) theory with either an
unscreened or screened interlayer interaction predicts a room temperature
condensate. Interlayer and intralayer interactions renormalize the
quasiparticle dispersion, and this effect is included in a GW approximation.
The renormalization reverses the trends predicted from the unscreened or
screened MF theories. In the strong coupling regime, intralayer interactions
have a large impact on the magnitude of the order parameter and its functional
dependencies on effective mass and carrier density.
