B-Mode Polarization Amplitude D₈₀ᴮᴮ

τ-Formula

D₈₀ᴮᴮ = first τ-polarization = 339 nK²

Derivation

With $r = ι_τ^4$ and $A_s = 2.096 × 10^-9$, the primordial B-mode power spectrum is fully determined. The recombination bump peaks at $ ≈ 80$:

D_80^BB \;=\; (+1)\,C_^BB2π |_ ≈ 80 \;≈\; 0.025 × r \;=\; 339\;nK^2.

At $ ≈ 80$, the lensing B-mode foreground ($∼ 0.3$ nK$^2$) is $∼ 1100×$ weaker than the primordial signal. De-lensing is not required. (Registry: V.D256, Wave 14F.)

Source

This prediction is derived in the Physics Ledger (Chapter 62 — inflation-cmb-bbn), Books IV–V of Panta Rhei.