The Atomki X17 Anomaly, Priced and Classified: Required Couplings, Exclusion Bookkeeping, and the Status of the Protophobic Vector Interpretation

Recomputation of the couplings a protophobic vector boson would require to explain the Atomki X17 excesses in 8Be, 4He and 12C, priced against NA64, PADME, FASER, (g-2)e, pi0 and charged-pion decay, neutron scattering and neutrino scattering limits. The 12C excess requires a nucleon coupling combination (0.0320) above the neutron-scattering bound (0.0197), and the electron window surviving NA64 and (g-2)e is closed for a pure vector boson by charged-pion decay combined with neutrino scattering. The anomaly is classified as a repeated measurement within a single experimental programme rather than an independent accumulation, and the settling measurement is specified.