V.T07 — Mass Ratio --- IV.T30

The neutron-to-electron mass ratio is R = iota_tau^(-7) - (sqrt(3) + pi^3 * alpha^2) * iota_tau^(-2), where alpha is the fine-structure constant. With iota_tau = 2/(pi+e) this gives R ~ 1838.684, matching R_CODATA = 1838.684 to 0.025 ppm with zero free parameters.