Charged Lepton Flavor Violation

We construct a list of minimal scale-invariant models at the TeV scale that generate one-loop neutrino mass and give viable dark matter candidates. The models generically contain a singlet scalar and a Z 2-odd sector comprised of singlet, doublet and/or triplet SU(2) multiplets. The dark matter may reside in a single multiplet or arise as an admixture of several multiplets. We find fifteen independent models, for which the dark matter is a viable candidate and neutrino mass results from a diagram with just one of the irreducible scale-invariant one-loop topologies. Further " non-pure " cases give hybrid one-/two-loop masses. All models predict new TeV scale physics, including a singlet scalar that generically mixes with the Higgs boson.

The proposed Mu2e experiment at Fermilab will search for evidence of charged lepton flavor violation
(CLFV) in the form of coherent conversion of a muon to an electron on an aluminum nucleus. The Mu2e detector will search for electrons with energy approximating the muon rest mass of 105.6 MeV using a system comprised of a straw tube tracker, crystal calorimeter, stopping target monitor, cosmic ray veto, and proton extinction monitor. The goal of this project was to determine an optimal photosensor for use with the BaF2 crystal calorimeter system including crystal and readout specification and testing. Photosensors used in this experiment include photomultiplier tubes (PMTs), avalanche photodiodes (APDs), and silicon photomultipliers (SiPMs). An optimal photosensor is defined as one which has enough timing resolution to discriminate between the fast and slow spectral components of BaF2, and must also operate in a 1 Tesla magnetic field. BaF2 crystals were coupled to each type of photosensor and tested in a light-tight box both with and without radiation sources. Further work is scheduled to test APDs and SiPMs which have a UV-extended epoxy coating.