Jeffrey M. Berryman

Sterile neutrino at the Deep Underground Neutrino Experiment

We investigate the potential for the Deep Underground Neutrino Experiment (DUNE) to probe the existence and effects of a fourth neutrino mass-eigenstate. We study the mixing of the fourth mass-eigenstate with the three active neutrinos of the Standard Model, including the effects of new sources of CP -invariance violation, for a wide range of new mass-squared differences, from lower than 10−5 eV to higher than 1 eV. DUNE is sensitive to previously unexplored regions of the mixing angle – mass-squared difference parameter space. If there is a fourth neutrino, in some regions of the parameter space, DUNE is able to measure the new oscillation parameters (some very precisely) and clearly identify two independent sources of CP -invariance violation. Finally, we use the hypothesis that there are four neutrino mass-eigenstates in order to ascertain how well DUNE can test the limits of the three-massive-neutrinos paradigm. In this way, we briefly explore whether light sterile neutrinos can serve as proxies for other, in principle unknown, phenomena that might manifest themselves in long-baseline neutrino oscillation experiments.

Solar neutrinos and the decaying neutrino hypothesis

We explore, mostly using data from solar neutrino experiments, the hypothesis that the neutrino mass eigenstates are unstable. We find that, by combining

Non-unitary neutrino propagation from neutrino decay

^8

Large, Extra Dimensions at the Deep Underground Neutrino Experiment

B solar neutrino data with those on

Lepton-number-violating searches for muon to positron conversion

^7

Standard model flavor from an

Be and lower-energy solar neutrinos, one obtains a mostly model-independent bound on both the

SU(2)

\nu_1

symmetry

and

Dark matter and neutrino mass from the smallest non-Abelian chiral dark sector

\nu_2

Imperfect mirror copies of the standard model

lifetimes. We comment on whether a nonzero neutrino decay width can improve the compatibility of the solar neutrino data with the massive neutrino hypothesis.