Multipole decomposition of the rate of muon-to-electron (μ-e-) conversion in Pb 208

CIVITARESE, O.; TARUTINA, T.

Physical Review C

American Physical Society

Año: 2019 vol. 99

2469-9985

The (μ-e-) conversion in Pb208 nucleus is studied. For the elementary process we consider the most general effective Lagrangian responsible for the lepton-flavor violation. For the nuclear structure part, the spectrum of Pb208 is calculated by performing a diagonalization of the δ-force interaction in the space of particle-hole pairs for neutrons and protons. We calculate the coherent contribution by direct summation of single-particle excitations. The noncoherent muon-to-electron conversion is calculated by summing over the contributions for all possible intermediate states in Pb208. We perform the multipole decomposition of the transition amplitude and present the nuclear matrix elements of spin-dependent and spin-independent operators appearing in the total rate of the muon to electron conversion process. The results are presented in a way to facilitate their use in model building of the electroweak process.