Speaker
Description
Should muon-to-electron conversion in the field of a nucleus be found in the current generation of experiments, the measurement of the atomic
number dependence of the process will become an important experimental
goal. We present a new treatment of the (Z,A) dependence of coherent
muon-to-electron conversion in 236 isotopes. Our approach differs from
earlier work in several ways. Firstly, we include the effect of
permanent quadrupole deformation on the charged lepton flavor violating
matrix elements, using the method of Barrett moments. This method also
enables the addition of muonic X-ray nuclear size and shape
determinations of the charge distribution to the electron scattering
results used previously. Secondly, we employ a Hartree-Bogoliubov model
to calculate neutron-related matrix elements for even-even nuclei,
instead of a simplistic scaling of the proton distribution by N/Z done
previously. This takes into account the fact that neutrons are, in
general, in different shell model orbits that protons. The calculated
conversion rate differ from previous calculations, particularly in the
region of large permanent quadrupole deformation. Finally, we introduce
an alternative normalization of the muon-to-electron conversion rate,
which relates more closely to what a given experiment actually measures,
and better separate lepton physics from nuclear physics effects.
| Working Group | WG 4: Muon Physics |
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