| Summary: | First, we propose a scale-invariant modified gravity interacting with a neutral scalar inflaton and a Higgs-like <inline-formula>
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</inline-formula> 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 the gravity-“inflaton” assisted dynamical spontaneous <inline-formula>
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</inline-formula> symmetry breaking in the post-inflationary universe, whereas the <inline-formula>
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</inline-formula> 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.
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