Completing our Picture of the Neutrino

Speaker:

Josh Spitz, Norman M. Leff professor of physics, Michigan University

 

Description:

Nearly 90 years after its proposed existence, the neutrino remains

largely mysterious and elusive. We don't know if matter neutrinos 

behave differently than antimatter neutrinos, we don't know which of

the neutrinos is heaviest, and we don't know how many types of

neutrinos there are.

The MiniBooNE short-baseline neutrino experiment has recently reported

a significant (4.5sigma) excess of electron-neutrino- like events in an

originally muon-neutrino beam. An oscillation interpretation of this

data would require at least four neutrino types and indicate new

physics beyond the three neutrino paradigm. MiniBooNE is not alone in

its anomalous observations of possible new neutrino mixing, as there

may be hints from other experiments as well. This talk will discuss

the recent MiniBooNE result, possible non-neutrino interpretations,

and prospects for future accelerator-based measurements. In

particular, Fermilab's Short-Baseline Neutrino (SBN) and the J-PARC

Sterile Neutrino Search at the J-PARC Spallation Neutron Source

(JSNS2) experiments will directly address these anomalies in the next

few years.

Along with discussing the recent MiniBooNE results and introducing SBN

and JSNS2, I will touch on the first measurement of the 236 MeV kaon

decay-at-rest neutrino, recently performed with MiniBooNE. The

significance of this and future studies, in terms of elucidating both

the neutrino-nucleus interaction and oscillations, will be emphasized.