Dynamical and Structural Decay of the Tau without Fermi Constant

The tau lifetime is determined within its orbital model, a hierarchical extension of the muonic model with entanglement closure on the experimental tau mass. The structure includes two additional inner weak orbitals (01, 02) and fully preserves the muonic component. All structural frequencies are calculated without external phenomenological parameters. Decay is described as a dynamical process emerging from the combination of primary selection and cumulative dissipation, both defined through a commensuration operator. Leakage is found to be high (q = 0. 90) in the time window of the fundamental channel (1, 2–1, 3), indicating that the mean lifetime is dominated by the selection rate. The latter takes the form FGate = pAlign · FMicro · R, where the factor R is determined by internal accessibility toward the targets and introduces no free parameters. Within the basin of solutions that preserve closure on mass and magnetic anomaly, the computed mean lifetime is stable, with value ~2. 90002 × 10-¹³ s, in agreement with the experimental datum within a relative error of order 10^-6. Tau decay is therefore interpretable as a collective property of its orbital architecture, coherent with the structural hierarchy: electron < muon < tau.