Appearance of Universal Metallic Dispersion in a Doped Mott Insulator

We have investigated the dispersion renormalization $Z_{disp}$ in La$_{2-x}$Sr$_x$CuO$_4$ (LSCO) over the wide doping range of $x=0.03-0.30$, for binding energies extending to several hundred meVs. Strong correlation effects conspire in such a way that the system exhibits an LDA-like dispersion which essentially `undresses ($Z_{disp}to 1$) as the Mott insulator is approached. Our finding that the Mott insulator contains `nascent or `preformed metallic states with a vanishing spectral weight offers a challenge to existing theoretical scenarios for cuprates.