Ab Initio Calculation of Nuclear Structure Effects in Light Muonic Atoms

Abstract

Nuclear structure effects to the Lamb shift in light muonic atoms are driven by the two-photon exchange contribution, whose evaluation relies significantly on nuclear theory. Using ab initio calculations, we have studied nuclear structure effects in several light muonic atoms, including $\mu ^{2,3}\mathrm {H}$ and $\mu ^{3,4}\mathrm {He}^+$ [1,2,3,4,5]. The two-photon exchange is associated with nuclear electromagnetic sum rules. The calculation was done with the implementation of state-of-the-art nuclear potentials, derived either phenomenologically or from chiral effective field theory. The statistical and systematic uncertainties from nuclear theory were analyzed by potential-model comparison, and by using power-counting and parameter-optimization techniques, that have been developed in chiral effective field theory. High precision of the ab initio results is crucial for accurately extracting nuclear charge radii in muonic atom spectroscopy.