Scientists Rule Out Elusive Sterile Neutrino After 10-Year Hunt, Shaking Particle Physics

Scientists have concluded, after ten years of painstaking measurements, that the sterile neutrino, whose existence has long been hypothesised, probably does not exist: a major shift in particle physics. Using the MicroBooNE experiment at Fermilab, researchers looked for that elusive particle in neutrinos from two strong beams and found no evidence of it, characterizing it as rejected with 95 percent confidence. The finding overturns a 10-year-old theory that was introduced to try and explain abnormal behaviour in neutrinos seen during earlier experiments. With this candidate now out of the picture, researchers are narrowing their quest for physics beyond the Standard Model and considering alternative explanations for the  neutrino anomalies.

MicroBooNE Experiment Rules Out Sterile Neutrino, Refining Focus on Neutrino Research and Future DUNE Studies

According to a Nature report, the research entailed Fermilab's MicroBooNE detector in Illinois. The international team, which included researchers from Rutgers University, studied neutrinos generated by two beams and monitored how they changed and interacted. But their conclusion offered no proof of a sterile neutrino and effectively ruled it out, eliminating one of the most hotly debated possibilities in the study of these particles and allowing scientists to move on to new paths to understand the particles' strange behaviour.

Neutrinos are relatively small particles that interact only weakly with matter and can travel through planets without being impeded. The Standard Model recognizes three varieties, i.e, electron, muon, and tau, that are capable of transforming from one type to another. Unlike the known types, a sterile neutrino would interact only through gravity, so it would be extremely difficult to detect.

The MicroBooNE team accounted for uncertainties such as neutrino-nucleus interactions, beam components, and detector responses. The results were checked by graduate researchers, and Mastbaum mentioned the work goes a long way to advance methods for future experiments, such as DUNE.