neutrinos

“Tested and verified with ever increasing precision,” the Standard Model is a a remarkably elegant way of understanding the relationships between particles and their interactions.” But then there are the neutrinos: In the Standard Model, neutrinos come in three kinds, or flavors: electron neutrinos, muon neutrinos and tau neutrinos. This mirrors the other matter particles in the Standard Model, which each can be organized into three groups. But some experiments have shown hints for a new type of neutrino, one that doesn’t fit neatly into this simple picture. … This extra neutrino—suggested by results from the Liquid Scintillator Neutrino Detector and the MiniBooNE experiment—wouldn’t match up with the generations of particles in the Standard Model. It would be “sterile,” meaning Read More ›

Recent cosmic ray activity in Antartica is  provoking question and speculation: Physicists don’t know what it is exactly. But they do know it’s some sort of cosmic ray — a high-energy particle that’s blasted its way through space, into the Earth, and back out again. But the particles physicists know about — the collection of particles that make up what scientists call the Standard Model (SM) of particle physics — shouldn’t be able to do that. Sure, there are low-energy neutrinos that can pierce through miles upon miles of rock unaffected. But high-energy neutrinos, as well as other high-energy particles, have “large cross-sections.” That means that they’ll almost always crash into something soon after zipping into the Earth and never make it Read More ›