We introduce Inflationary Domain Theory (IDT), a minimal effective extension of ΛCDM in which epoch-localized energy density contributions modify the expansion history and structure growth at specific cosmological epochs. A key feature is an effective Friedmann-Poisson decoupling: domain contributions modify background expansion without correspondingly enhancing local gravitational clustering. A two-domain architecture is implemented in the CLASS Boltzmann solver — an early domain (z ∼ 2000) correcting the CMB acoustic scale, and a late domain (z ∼ 1) suppressing structure growth via a dephasing mechanism. With only two extra parameters beyond ΛCDM, the model achieves ΔAIC = −8.1, reducing the acoustic scale tension from 3.1σ to 0.3σ and shifting H0 from 67.4 to 68.7 km s⁻¹ Mpc⁻¹. The two channels operate with approximate independence, a feature not naturally reproduced by Early Dark Energy or wCDM within minimal parameterizations.
Jose Ramon Gonzalez (Wed,) studied this question.