Fine-structure constant and electron g-2 consistency

3 problems

• Origin of the $5\,\sigma$ gap between cesium and rubidium $\alpha$

  Open

  Two labs measured $\alpha$ by timing how fast an atom moves after absorbing a photon, one with cesium and one with rubidium, and their answers differ by more than five times their stated errors. At least one experiment has an error nobody has found.

• Is the electron magnetic moment anomaly consistent with the Standard Model?

  Open

  The electron behaves like a tiny magnet whose strength has been measured to about one part in ten trillion. Using $\alpha$ from atom experiments, theory predicts the same number, and any mismatch would point to new particles or forces.

• An independent third determination of $\alpha$ at 0.1 ppb

  Open

  With two top measurements disagreeing, a third method that shares none of their possible errors could tell which one is wrong. Candidates use other atoms, such as strontium or ytterbium, or the fine splitting of helium energy levels.