In case you were wondering what I work on, KEK (the Japanese high energy physics lab) released a video on the T2K experiment last week. I think it gives a pretty good general explanation for laypeople of the experiment and the physics it’s studying.
Sadly, I don’t think I appear anywhere in the video (maybe in one of the group pictures), but I know some of the people who do.
The short explanation is that there are 3 flavors (types) of neutrinos (electron, muon, and tau neutrinos), which have very small but non-zero mass. As they travel, the neutrinos can change from one flavor to another. We create a beam composed mostly of muon neutrinos (or antineutrinos) at the J-PARC facility in Tokai, Ibaraki and measure neutrino interactions a few hundred meters from the target and again a few hundred kilometers away at the Super-Kamiokande detector in the Kamioka mine near Toyama. This lets us study how the neutrinos change flavor. This is generally known as neutrino oscillations and is one of several active neutrino research topics in high energy and nuclear physics.