R-layer Mode Theory (RLMT) LXXV: Nonperturbative Transitions, Instantons, and Fragmentation in the R-layer Universe

This volume develops a nonperturbative description of transitions in the unstable regime of layer 28 in R-layer Mode Theory. Using an effective single-field representation of the relevant R-layer mode, we construct O(4)-symmetric instanton solutions, derive thin-wall analytic expressions for the critical radius and instanton action, and compute systematic corrections beyond the thin-wall limit. The resulting decay rate governs fragmentation and tunneling processes in the R-layer stack, providing the microscopic foundation for subsequent volumes.