David Nygren (University of Texas Arlington): The quest for the nature of the neutrino: particle/antiparticle, or neither?

The Standard Model of particle physics is silent on whether the neutrino is its own antiparticle or not. The only practical experimental approach to this question lies in the search for neutrinoless double beta decay, an extremely rare second-order transition allowed only if the neutrino has non-zero rest mass and is its own antiparticle. The discovery of neutrino oscillations has demonstrated that neutrinos do have a tiny but non-zero neutrino rest mass and has set a scale for experimental searches. All experiments struggle to mitigate backgrounds from radioactivity that can mimic signal. A diverse variety of experimental approaches has been developed around a half-dozen isotopes that offer appealing properties for the search. A robust positive signal found, in any isotope, will have profound implications for particle physics and cosmology. I will describe the uses of the isotope 136Xe within the broad global race toward discovery.