n_light_quarks

The module treats the QED running of the fine-structure constant from $q^2=0$ to $q^2=M_Z^2$ as the dominant radiative correction to electroweak mass predictions. Recognition Science fixes $\alpha^{-1}(0)\in(137.030,137.039)$ from the forcing chain; PDG supplies $\alpha^{-1}(M_Z)\approx 127.951$, so the running ratio must lie in $(0.933,0.935)$.

That ratio is not free: the one-loop vacuum polarization $\Delta\alpha=\alpha/(3\pi)\sum_f N_c Q_f^2[\log(M_Z^2/m_f^2)-5/3]$ sums over the particle content below $M_Z$. The light quarks in that sum are the five flavors lighter than the Z (top is integrated out). The companion constant counts three charged leptons. Together they close the free-parameter count for the scorecard.

Pure definitional assignment: the natural number five is bound to the name. No tactics, no lemmas, no reduction. Downstream equalities simply unfold this constant.

Feeds the certificate structure AlphaRunningCorrectionScoreCardCert, whose field quarks asserts equality to five alongside the lepton count, the $\alpha^{-1}(0)$ band, and the running-ratio band. The module claims zero additional free parameters once particle content is fixed; this constant is half of that content ledger (with three charged leptons). It sits under the RS $\alpha$ band from the forcing chain and under the claim that the corrected VEV from RS-native $\alpha(0)$ lands in the PDG window. Without a fixed $N_q^{\mathrm{light}}$, the vacuum-polarization sum would reintroduce a free integer into the running correction.