Using high resolution angle-resolved photoemission data in conjunction with
that from neutron and other probes, we show that electron-phonon (el-ph)
coupling is strong in cuprates superconductors and it plays an important role
in pairing. In addition to the strong electron correlation, the inclusion of
phonons provides a theoretical framework explaining many important phenomena
that cannot be understood by a strongly correlated electronic model alone.
Especially it is indispensable to explain the difference among materials. The
phonons with the wave number around the (0,qx) and (qx,0) axes create the
d-wave pairing while that near (pi,pi) are pair breaking. Therefore the
half-breathing mode of the oxygen motions helps d-wave superconductivity.Comment: 10 pages, 4 figure
