The Left-Handed Universe: An Evidential Audit of the Broken Symmetry Assumption

The Standard Model treats the left-handedness of the weak interaction as a spontaneously broken symmetry — the remnant of an originally parity-symmetric universe whose symmetry was hidden by the Higgs mechanism. This paper audits the evidential basis for that assumption. The TWIST experiment measured the parity asymmetry parameter in muon decay to P_μ^π·ξ = 1.00084 ± 0.00029, consistent with exactly 1 — maximal parity violation with zero right-handed component to six decimal places. Every weak interaction ever observed is exclusively left-handed. No right-handed neutrino has been detected. The minimal sterile neutrino model was excluded by MicroBooNE in December 2025 (95% CL). Neutrinoless double-beta decay…