  We investigate the electronic dispersion of the high-T$_{\mathrm{c}}$ cuprate
superconductors using the fully self-consistent version of the phenomenological
model, where charge planar quasiparticles are coupled to spin fluctuations. The
inputs we use ---the underlying (bare) band structure and the spin
susceptibility $\chi$--- are extracted from fits of angle resolved
photoemission and inelastic neutron scattering data of underdoped
YBa$_{2}$Cu$_{3}$O$_{6.6}$ by T. Dahm and coworkers (T. Dahm et al., Nat. Phys.
5, 217 (2009)). Our main results are: (i) We have confirmed the finding by T.
Dahm and coworkers that the main nodal kink is, for the present values of the
input parameters, determined by the upper branch of the hour-glass of $\chi$.
We demonstrate that the properties of the kink depend qualitatively on the
strength of the charge-spin coupling. (ii) The effect of the resonance mode of
$\chi$ on the electronic dispersion strongly depends on its kurtosis in the
quasimomentum space. A low (high) kurtosis implies a negligible (considerable)
effect of the mode on the dispersion in the near-nodal region. (iii) The energy
of the kink decreases as a function of the angle $\theta$ between the Fermi
surface cut and the nodal direction, in qualitative agreement with recent
experimental observations. We clarify the trend and make a specific prediction
concerning the angular dependence of the kink energy in underdoped
YBa$_{2}$Cu$_{3}$O$_{6.6}$.

Superconductivity