Coupling Of The B1g Phonon To The Anti-Nodal Electronic States of   Bi2Sr2Ca0.92Y0.08Cu2O(8+delta)
  Angle-resolved photoemission spectroscopy (ARPES) on optimally doped Bi2Sr2Ca0.92Y0.08Cu2O(8+delta) uncovers a coupling of the electronic bands to a 40 meV mode in an extended k-space region away from the nodal direction, leading to a new interpretation of the strong renormalization of the electronic structure seen in Bi2212. Phenomenological agreements with neutron and Raman experiments suggest that this mode is the B1g oxygen bond-buckling phonon. A theoretical calculation based on this assignment reproduces the electronic renormalization seen in the data. 
T. Cuk, F. Baumberger, D.H. Lu, N. Ingle, X.J. Zhou, H. Eisaki, N.   Kaneko, Z. Hussain, T.P. Devereaux, N. Nagaosa, Z.-X. Shen