Nodal quasiparticle dispersion in strongly correlated d-wave superconductors -: art. no. 144509

We analyze the effects of a k-dependent self-energy on the photoemission momentum distribution curve (MDC) line shape and dispersion and, in particular, show that this modifies the "high-energy" dispersion v(F)(high) of the MDC's in an essential way. These general results are illustrated by a detailed examination of nodal quasiparticles in the superconducting state of the high-T-c cuprates. Using variational results for the nodal quasiparticle weight Z, which vanishes with the hole doping x, and the low energy dispersion v(F)(low), which is independent of x, we show that the "high-energy" dispersion v(F)(high)=v(F)(low)/Z is much larger than the band structure value and exhibits a striking doping dependence in good agreement with recent data. These results provide strong evidence for an electronic origin of all the nodal dispersion anomalies, including the much-studied kink.