−0.08 −0.06 −0.04 −0.02 0 0.02 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 Binding Energy (meV) Counts 0.4 0.42 0.44 0.46 0.48 500 1000 1500 2000 2500 k$_{|}$$_{|}$ (Inverse Angstroms) Counts a) b) FIG. 3. (Color online) a) EDC’s at k F from the original data of Figure 1a (open circles) and deconvolved data of Figure 1d (dots). b) MDC’s at E F from the original data of Figure 1a (circles) and deconvolved data of Figure 1d (dots). and MDC’s is clearly evident in the comparison. Further, the shift in the peak position of the MDC with deconvolution is indicative of the Fermi velocity also being corrected by this procedure. The widths obtained from Lorentzian fits of the deconvolved EDC and MDC are shown in Figure 4. The improvement of both the overall shape as well as widths of the peaks is self-evident. As will be shown below, the broadening of the band at binding energies greater than the kink energy is in fact the result of an interaction between electrons in the bonding band with a well defined low energy bosonic mode. This interaction produces a renormalization of the real and imaginary parts of the electron self energy, a ”kink”, that itself disperses at fixed energy with respect to the bottom of the d-wave superconducting gap. Because the observed mode sets in at such low energies and causes rapid changes in the band dispersion over a very small energy range an analysis of momentum distribution curves (MDC’s) does not suffice to extract the imaginary part of the self energy. MDC IV. ANALYSIS OF DECONVOLVED DATA 6