We show that the double kink-structure in the electronic self-energy of Bi2212 near the nodal point at low energy ω1≈50−70meV and at high energy at ω2≈350meV, observed recently in the ARPES measurements by Valla et al \cite{Valla-2006}, gives that the electron-phonon (EPI) coupling constant λzEPin the normal part of the self-energy Σ(ω) is twice larger than the Coulomb coupling λzC. The experimental data for \funcReΣ(ω) up to energies ∼350meV can be satisfactory explained by and λzC≈1.1. Additionally the low energy slope of the ARPES \funcReΣ(ω) at ω<20meV \cite{Valla-2006} gives a hint that the low energy phonons might contribute significantly to the EPI coupling, i.e. λzlow,EP>1, thus giving the total EPI coupling constant λz,totEP=λzEP+λzlow,EP>3. In order to test the role of low frequency phonons by ARPES measurements a much better momentum resolution is needed than that reported in \cite{Valla-2006}. Possible pairing scenarios based on ARPES, tunnelling and magnetic neutron scattering measurements are discussed.
@article{arxiv.cond-mat/0610549,
title = {ARPES Spectra of Bi2212 give the Coulomb Coupling $\lambda ^{C}\approx 1$ and the Electron-Phonon Coupling $\lambda ^{EP}=2-3$},
author = {Miodrag L. Kulic and Oleg V. Dolgov},
journal= {arXiv preprint arXiv:cond-mat/0610549},
year = {2007}
}