V.D256 — Primordial B-Mode Amplitude from r = iota_tau^4

Primordial B-mode amplitude: D_80^BB = 0.025*r = 339 nK^2 at ell~80 (recombination bump). A_t = r*A_s = 2.844e-11. Lensing foreground at ell~80 is 1131x weaker. From r = iota^4 (tau-effective) and A_s = 2.096e-9 (tau-effective).