Microscopic Origin of QIMG Thermalisation: From the Thermalisation Lagrangian Lₓ₇ to Channel Rates ᵢ (T)

Quantum-Informational Metric Genesis Cosmology (QIMG Cosmology) was introduced as a post-FRW extension of the Cyclic Black Hole Information Reintegration Theory (CBHIRT). In this framework, CBHIRT supplies the pre-geometric informational initial conditions inherited from Page-time black-hole correlations, while QIMG describes how this inherited structure may be represented after FRW activation as an effective metric geometry and an informational stress-energy tensor, \ T^info_[I. \] A subsequent thermalisation module proposed that this effective QIMG stress-energy representation may enter a controlled realisation regime and become physically expressed as radiation, matter, entropy, temperature, and hot primordial plasma. However, that module remained primarily phenomenological: it introduced a thermalisation map, a residual sector, a physically realised sector, and channel rates, but did not yet derive these structures from an underlying microscopic or action-level formulation. The present work develops the next layer of the CBHIRT--QIMG programme by proposing an effective microscopic origin for QIMG thermalisation. Its central aim is to construct a covariant thermalisation action \ Sₓ₇ = d⁴x -g\, Lₓ₇, \ from which the transfer current \ J^th_ \ and the temperature-dependent channel rates \ ᵢ (T) \ may be systematically motivated. The object undergoing thermalisation is not raw information itself, but the residual QIMG stress-energy representation \ T^res_ = (1-ₓ₇) T^info_, \ which acts as a pre-thermal effective reservoir after FRW activation. The physically realised sector is described by \ T^phys_ = T^rad_ + T^matter_ + T^plasma_, \ where the plasma tensor represents collective interaction and coupling effects rather than a double counting of radiation and matter. The paper formulates a thermalisation Lagrangian density containing residual-sector operators, channel operators, coupling scales, and covariant response functions. The transfer current is derived from the variation of the effective action and interpreted as the covariant flow of stress-energy representation from the residual QIMG sector into physical radiation, matter, and plasma channels. The corresponding channel rates are expressed schematically as \ ᵢ (T) = ₓ₇^₈ ᵢ² ₓ₇² \, ₑ₄ₒ\, T^ₑ₄ₒ T^ₑ₄ₒ ₈, (T), \ where \ (₈, (T) \) denotes the finite-temperature spectral response of the physical channel \ (i\), and the brackets indicate coarse-grained thermal averaging. This construction does not claim a direct conversion of information into energy. Instead, it provides an action-based mechanism by which an already established QIMG stress-energy representation may become physically realised through covariant thermalisation channels. In this sense, the present work supplies the microscopic completion of the previous thermalisation module and connects the CBHIRT--QIMG informational-geometric hierarchy to the Hot Big Bang radiation--matter plasma phase.