Speaker
Description
Laser spectroscopy of muonic atoms has been recently used to probe the low-energy properties of the proton and light nuclei with unprecedented precision [1]. In the future, measurements of the Lamb shift in muonic hydrogen and helium isotopes are supposed to improve by up to a factor 5. Furthermore, there is an ongoing effort to perform a first-time measurement of the ground-state hyperfine splitting in muonic hydrogen with ppm accuracy. In order to extract with high precision nuclear radii or polarizability effects from the spectroscopy measurements, the experimental accuracy has to be matched by the corresponding theoretical predictions. Thus, it is a timely task to refine the theoretical predictions [2], and in particular, the nucleon-structure contributions.
After a brief overview of the theory of light muonic atoms and related experiments, I will discuss the effect of the nucleon polarizabilities on the spectra of muonic atoms through forward two-photon exchange. I will present the recent NLO baryon chiral perturbation theory prediction of doubly-virtual Compton scattering and the nucleon polarizabilities [3], as well as the proton polarizability contribution to the Lamb shift [4] and hyperfine splitting [5] of muonic hydrogen. Some ideas to further reduce uncertainty on the nucleon structure contributions will be discussed [6,7].
[1] Antognini et al., Ann. Rev. Nucl. Part. Sci. 72 (2022) 389
[2] Pachucki et al., Rev. Mod. Phys. 96 (2024) 1, 015001
[3] Alarcon et al., Phys. Rev. D 102 (2020) 11, 114026 and Phys. Rev. D 102 (2020) 1, 014006
[4] Alarcon et al., Eur. Phys. J. C 74 (2014) 4, 2852
[5] Hagelstein et al., Eur. Phys. J. C 83 (2023) 8, 762
[6] Hagelstein et al., Nucl. Phys. A 1016 (2021) 122323
[7] Biloshytskyi et al., Phys. Rev. D 109 (2024)
