On the dynamic distinguishability of nodal quasi-particles in overdoped cuprates

La₁. ₆₇Sr₀. ₃₃CuO₄ is not a superconductor and its resistivity follows a purely T² temperature dependence at very low temperatures. La₁. ₇₁Sr₀. ₂₉CuO₄, on the other hand, has a superconducting ground state together with a T-Linear term in its resistivity. The concomitant emergence of these two features below a critical doping is mystifying. Here, I notice that the electron-electron collision rate in the Fermi liquid above the doping threshold is unusually large. The scattering time of nodal quasi-particles expressed in a dimensionless parameter is very close to what has been found in liquid ³He at its melting pressure. In the latter case, fermionic particles become dynamically distinguishable by excess of interaction. Ceasing to be dynamically indistinguishable, nodal electrons will be excluded from the Fermi sea. Such non-degenerate carriers will then scatter the degenerate ones within a phase space growing linearly with temperature.