Fig. 4.

Energy dispersions for characteristic scattering wave vectors and superconducting gap. a Superconducting gap Δ(θ) (circles) and two fitting curves by different d-wave gap functions. The inset in a shows the positions of the ends of CCE determined by q₁ and q₇ measured at various energies. The solid line shows the Fermi surface from the fitting to these positions by a circular arc, and it is cut off by the dashed line. The angle θ for each end of CCE is defined in the inset. The gap value Δ for each end of CCE is equivalent to the energy at which the QPI data are measured. b Energy dispersion of the scattering wave vectors taken from the FT-QPI data (excluding q₄ due to very weak intensity). The solid lines represent the theoretical predictions based on the Fermi surface and the d-wave gap function with high order shown by the line with magenta color in a