of the spectra of Fig. \[fig:dimer\_transition\_spectra\] and we replot the DOS in Fig. \[fig:transition\_spectra\_scaling\] as a function of the rescaled frequency $\omega/ ZD$. We see that a clear picture emerges, where the central peak can be understood as two bands whose splitting is renormalized down but whose width is also renormalized down. The R2B model parametrization (in dashed red line in the figure) provides a good representation of the lowest frequency part of the spectra, made by the low energy edges of the B and AB peaks. Otherwise, is not very accurate.

Unlike in the Brinkman-Rice scenario, where $Z \to 0$, here the transition occurs at a finite effective mass. The opening of the gap results from the combined effect of the renormalization of the bandwidth and of the splitting. Both decrease as $U \to U_{c_2}(t_\perp)$, but the quantity that becomes zero is not $Z$ but the renormalized B/AB band overlap $\eta =
ZD - Z\tilde{t}_\perp$. This means that the low-energy B and AB contributions to the quasi-particle peak separate. This behavior is similar to the MIT reported in a correlated two orbital model [@mazza2016_field_driven_mott_gap_collapse]. Despite the lack of a mass divergence, the transition does share a similarity with the 