Non-Fermi liquid scattering against preformed pairs: manifestations in the kink and other exotic quasiparticle behaviors in the normal-state cuprate superconductors

The normal state of cuprate superconductors exhibits many exotic behaviors[1][2] qualitatively different from the Fermi liquid, the foundation of condensed matter physics. Here we demonstrate that non-Fermi liquid (NFL) behaviors emerge naturally from scattering against a two-orbital bosonic liquid of tightly-bound pairs. Particularly, we find a finite zero-energy scattering rate at low-temperature limit that grows linearly with respect to temperature, against clean fermions' generic non-dissipative characteristics. Surprisingly, three other seemingly unrelated experimental observations are also produced, including the well-studied "kink"[3-9] in the quasi-particle dispersion, as well as the puzzling correspondences between the normal and superconducting state[10,11]. Our findings provide a general route for fermionic systems to generate NFL behavior, and suggest strongly that the cuprates be in this exotic regime in which doped holes develop bosonic characteristics by forming tightly bound pairs, whose low-temperature condensation gives unconventional superconductivity.