Neutron as minimal stable defect

The neutron is the minimal stable defect-bundle equivalence class on the carrier: the lightest defect regime whose internal address and holonomy structure closes under the E_1 microphysical grammar. Beyond being one particle among others, it is the parent carrier regime from which atomic matter differentiates. Its mass supplies the sole dimensional SI calibration anchor: one dimensional scale-setting parameter that connects the dimensionless τ-internal coupling ledger to laboratory units.