  First, we propose a scale-invariant modified gravity interacting with a
neutral scalar "inflaton" and a Higgs-like SU(2)xU(1) iso-doublet scalar field
based on the formalism of non-Riemannian (metric-independent) spacetime
volume-elements. This model describes in the physical Einstein frame a
quintessential inflationary scenario driven by the "inflaton" together with
gravity-inflaton assisted dynamical spontaneous SU(2)xU(1) symmetry breaking in
the post-inflationary universe, whereas SU(2)xU(1) symmetry remains intact in
the inflationary epoch. Next, we find the explicit representation of the latter
quintessential inflationary model with a dynamical Higgs effect as an
Eddington-type purely affine gravity.
