title: Evidence for an energy scale for quasiparticle dispersion in Bi2Sr2CaCu2O8
abstract: Quasiparticle dispersion in Bi2Sr2CaCu2O8 is investigated with improved angular resolution as a function of temperature and doping. Unlike the linear dispersion predicted by the band calculation, the data show a sharp break in dispersion at 50+/-15 meV binding energy where the velocity changes by a factor of 2 or more. This change provides an energy scale in the quasiparticle self-energy. This break in dispersion is evident at and away from the d-wave node line, but the magnitude of the dispersion change decreases with temperature and with increasing doping.
authors.affiliation: Department of Physics, Applied Physics and Stanford Synchrotron Radiation Laboratory, Stanford University, Stanford, California 94305, USA.
authors.initials: PV
authors.lastname: Bogdanov
authors.initials: A
authors.lastname: Lanzara
authors.initials: SA
authors.lastname: Kellar
authors.initials: XJ
authors.lastname: Zhou
authors.initials: ED
authors.lastname: Lu
authors.initials: WJ
authors.lastname: Zheng
authors.initials: G
authors.lastname: Gu
authors.initials: J
authors.lastname: Shimoyama
authors.initials: K
authors.lastname: Kishio
authors.initials: H
authors.lastname: Ikeda
authors.initials: R
authors.lastname: Yoshizaki
authors.initials: Z
authors.lastname: Hussain
authors.initials: ZX
authors.lastname: Shen