Measurement of the fine-structure constant as a test of the Standard Model

Measuring the fine-structure constant $\alpha$ allows testing the consistency of theory and experiment across physics. Using the recoil frequency of cesium-133 atoms in a matter-wave interferometer, we recorded the most accurate measurement of the fine-structure constant to date: $\alpha = 1/137.035999046(27)$ at $2.0 \times 10^{-10}$ accuracy. Comparison with Penning trap measurements of the electron gyromagnetic anomaly $g_e-2$ via the Standard Model of particle physics is now limited by the uncertainty in $g_e - 2$. Implications for dark-sector candidates and electron substructure may be a sign of physics beyond the Standard Model that warrants further investigation.