Hadronic vacuum polarization effect in muonic atoms

Abstract: The hadronic vacuum polarization (HVP) corrections to energy levels in muonic atoms are studied systematically across the periodic table. Two nuclear charge distribution models have been considered, with partly analytical solution for an homogeneously charged sphere model and direct numerical integration for a Fermi nuclear charge distribution. Our comparison reveals a good agreement between both approaches with differences typically below a few percent. The magnitude of HVP corrections increases with nuclear charge, displaying irregularities that correlate directly with the non-monotonic behavior of nuclear radii. Despite strong relativistic effects at high $Z$, the ratio of hadronic to muonic vacuum polarization remains remarkably stable, deviating by less than $10\%$ from the established $67\%$ non-relativistic benchmark value