New calculations seem to have put a 25-year-old particle physics puzzle to rest. But they’ve also created a clash with other experimental results. Introduction For 25 years, physicists have been puzzled by an apparent one-part-in-a-million problem. Their expectations of the way that certain particles should wobble in a magnetic field were clashing with what they saw in experiments. The discrepancy was an electrifying hint that they might be seeing evidence of unknown particles. Then in 2021, tha...