Registry · Definition
IV.D291
tau-effective
formalized
IV.D291 — Calibration Anchor
The calibration anchor of Category tau physics is the neutron mass m_n = 1.674927500(83) x 10^(-27) kg (CODATA 2022), with relative standard uncertainty 5.0 x 10^(-8). This single experimental value anchors the entire tau-physics dimensional framework.