Two Beams, One Detector: Chasing the Sterile Neutrino with MicroBooNE

For more than three decades, several neutrino experiments have reported puzzling results that do not fit within the standard three-neutrino picture, motivating the idea of a sterile neutrino. These hints have raised the possibility that neutrinos may be more complex than currently understood, but testing this idea has proven challenging.

In this colloquium, I will describe how the MicroBooNE experiment takes a new approach to this problem. By observing neutrinos from two different accelerator beams in the same detector—a “two beams, one detector” strategy—MicroBooNE can compare their behavior in a particularly direct way. Using this approach, MicroBooNE finds no evidence for a light sterile neutrino and rules out the regions suggested by earlier experiments such as LSND and MiniBooNE. I will briefly place this result in the broader context of ongoing searches for sterile neutrinos, including recent complementary constraints from the KATRIN experiment.