Figure 2. Disagreement between the ARPES results and the conventional BCS gap function.

(a,b) Temperature dependence of spectral peak energy, ɛ_peak(T), at various k_F points (colour circles in the insets) for OP92K and OD72K, respectively. In the bottom of each panel, the same curves of ɛ_peak(T) are normalized to the maximum value at the lowest temperature. A red dashed curve and a green solid curve are the BCS gap function with the onset at T_c and T_pair, respectively (T_pair=135 K for OP92K and T_pair=89 K for OD89K). The inset shows the Fermi surface with measured k_F points (colour circles). The bold orange line indicates the momentum region where the Fermi arc was previously claimed to emerge at T_c. Error bars in a and b represent standard deviations of the spectral peak positions.