Fractionalized Fermi liquids with the ghost-Gutzwiller Ansatz

Fractionalized Fermi liquids (${\mathrm{F}\mathrm{L}}^{\text{\hspace{0.17em}⁣}\ast }$), elusive metallic states characterized by fractionalized quasiparticles alongside conventional ones and defying Luttinger’s theorem, are prime candidates for the pseudogap regime of underdoped cuprates. We show that a ${\mathrm{F}\mathrm{L}}^{\text{\hspace{0.17em}⁣}\ast }$ phase emerges in the single-band $t$-$J$ model through a simple ghost-Gutzwiller Ansatz, optimized at the cost of a mean-field calculation. The resulting temperature-doping phase diagram encompasses a low-doping ${\mathrm{F}\mathrm{L}}^{\text{\hspace{0.17em}⁣}\ast }$, a $d$-wave superconducting dome, and an overdoped conventional Fermi liquid, thereby reproducing key qualitative features of cuprate phenomenology.