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DOE OSTI · 3004302

Ab initio calculations of overlap integrals for μ → e conversion in nuclei

Heinz, Matthias [Technical Univ. of Darmstadt (Germany); GSI-Helmholtzzentrum fur Schwerionenforschung, Darmstadt (Germany); Max Planck Inst. fuer Kernphysik, Heidelberg (Germany); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000263630056)·Hoferichter, Martin [Univ. of Bern (Switzerland)] (ORCID:0000000311139377)·Miyagi, Takayuki [Univ. of Tsukuba (Japan); Technical Univ. of Darmstadt (Germany); GSI-Helmholtzzentrum fur Schwerionenforschung, Darmstadt (Germany); Max Planck Inst. fuer Kernphysik, Heidelberg (Germany)] (ORCID:0000000265294164)·Noël, Frederic [Univ. of Bern (Switzerland)] (ORCID:0000000274507213)·Schwenk, Achim [Technical Univ. of Darmstadt (Germany); GSI-Helmholtzzentrum fur Schwerionenforschung, Darmstadt (Germany); Max Planck Inst. fuer Kernphysik, Heidelberg (Germany)] (ORCID:0000000180274076)
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Abstract

The rate for μ → e conversion in nuclei is set to provide the most stringent test of lepton-flavor symmetry and a window into physics beyond the Standard Model. However, to disentangle new lepton-flavor-violating interactions, in combination with information from μ → ey and μ → 3e, it is critical that uncertainties at each step of the analysis be controlled and fully quantified. In this regard, nuclear response functions related to the coupling to neutrons are notoriously problematic, since they are not directly constrained by experiment. We address these shortcomings by combining ab initio calculations with a recently improved determination of charge distributions from electron scattering by exploiting strong correlations among charge, point-proton, and point-neutron radii and densities. We present overlap integrals for 27 Al, 48 Ca, and 48 Ti including full covariance matrices, allowing, for the first time, for a comprehensive consideration of nuclear structure uncertainties in the interpretation of μ → e experiments.

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Heinz, Matthias [Technical Univ. of Darmstadt (Germany); GSI-Helmholtzzentrum fur Schwerionenforschung, Darmstadt (Germany); Max Planck Inst. fuer Kernphysik, Heidelberg (Germany); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)] (ORCID:0000000263630056), Hoferichter, Martin [Univ. of Bern (Switzerland)] (ORCID:0000000311139377), Miyagi, Takayuki [Univ. of Tsukuba (Japan); Technical Univ. of Darmstadt (Germany); GSI-Helmholtzzentrum fur Schwerionenforschung, Darmstadt (Germany); Max Planck Inst. fuer Kernphysik, Heidelberg (Germany)] (ORCID:0000000265294164), Noël, Frederic [Univ. of Bern (Switzerland)] (ORCID:0000000274507213), Schwenk, Achim [Technical Univ. of Darmstadt (Germany); GSI-Helmholtzzentrum fur Schwerionenforschung, Darmstadt (Germany); Max Planck Inst. fuer Kernphysik, Heidelberg (Germany)] (ORCID:0000000180274076). 2025-10-27. Ab initio calculations of overlap integrals for μ → e conversion in nuclei. https://doi.org/10.1016/j.physletb.2025.139975

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