Experimental evidence indicates that the superconducting transition
in high $T_c$ cuprates is an 'undressing' transition. Microscopic
mechanisms giving rise to this physics were discussed in the
first paper of this series. Here we discuss the calculation of the
single particle Green's function and spectral function for Hamiltonians
describing undressing transitions in the normal and superconducting
states. A single parameter, $\Upsilon$, describes the strength of the
undressing process and drives the transition to superconductivity.
In the normal state, the spectral function evolves from
predominantly incoherent to partly coherent as the hole concentration
increases. In the superconducting state,
the 'normal' Green's function acquires a contribution from the anomalous
Green's function when $\Upsilon$ is non-zero; the resulting contribution
to the spectral function is $positive$ for hole extraction and
$negative$ for hole injection. It is proposed that these results
explain the observation of sharp quasiparticle states in the
superconducting state of cuprates along the $(\pi,0)$ direction
and their absence along the $(\pi,\pi)$ direction.
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