Continuous Cosmic Reemergence through Longitudinal Boundary States: An Extension of the ΛCDM Model

In ΛCDM, expansion asymptotically approaches a de Sitter regime . This work develops a phenomenological extension of the expanding cosmological branch described by general relativity and Friedmann–Lemaître–Robertson–Walker geometry. To address observed matter predominance and the absence of widespread matter–antimatter annihilation signals, the construction considers conjugate matter- and antimatter-dominated regions initially separated by a finite dark-sector-only interface. Bilateral advance over this interface progressively incorporates its dark-sector content into the growing regional volumes. This supplies the scenario’s proposed physical interpretation of increasing regional dark-energy content at approximately constant or slowly varying density. The acceleration equation identifies the negative-pressure condition that supports accelerated expansion, while an explicit de Sitter example demonstrates the kinematic compatibility of accelerated expansion with disappearance of the separating strip. Subsequent matter–antimatter overlap permits annihilation; expansion then dilutes and redshifts radiation, reducing access to selected transverse excitation channels while spatial geometry remains three-dimensional. Two residual conjugate excitations and a preexisting longitudinal field approach a common energetic profile through the proposed separation and dilution process. Critical collective materialization admits the corresponding BX and BM descriptions, with instantaneous macroscopic stationarity and retained microscopic states. Continued central neutralization in BM releases energy into radiation and allowed transverse channels. Alternating growth of the conjugate domains and of their interface maintains spatial separation during exhaustion of the longitudinal source, preparing hot regions whose subsequent mean evolution follows standard cosmology. The construction maintains local covariant conservation, consistent pressure–volume and boundary accounting, and a non-decreasing entropy budget. It establishes a conditional explanatory route connecting accelerated expansion, longitudinal boundary organization, reemergence and possible macroscopic recurrence without an entropy reset or global contraction.