Have Balloons and Ice Broken the Standard Model?
For something called the Standard Model, the foundational theory of particle physics is confronting a lengthy list of non-standard data. Neutrino oscillations, dark matter and energy, the imbalance between matter and anti-matter, quantum gravity—there’s a growing list of natural phenomena that don’t seem to fit.
Now there might be a new entry. Two years ago, a balloon-born experiment floating high above the Antarctic ice looking for neutrinos saw something unusual: particle signatures traveling up out of the Earth at angles suggesting that they’d passed through 5000 kilometers of rock. The particles had energies that were high enough for the Standard Model to prohibit that kind of careless disregard for matter.
The data gave rise to a series of speculations. Some, like decaying dark matter inside the Earth, or a new form of neutrino, represented new physics beyond the Standard Model. Others were more mundane: The signals could have resulted, for example, from some unconsidered physics that made a regular, downward-going neutrino look as if it were traveling up.
Then, two weeks ago, a team of physicists from Penn State University pointed out that the two ANITA detections, plus three unusual neutrino detections at a completely different experiment—called IceCube, also in Antarctica—could all be explained by a chain of particle collisions and decays that involved the stau.
The stau is a hypothesized, never-detected particle that is proposed by supersymmetry. According
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