For decades physicists have sought signs of misbehaving particles—evidence of subtle cracks in the “Standard Model” of particle physics, the dominant theory describing the most fundamental building blocks of our universe. Although the Standard Model has proved strikingly accurate, scientists have long known some adjustments will be needed. Now, as a recent review paper in Nature documents, experimenters have started seeing suggestions of particles flouting the theory—but they’re not quite the violations theorists were looking for.

The evidence comes from electrons and their more massive cousins, muons and tau leptons. According to the Standard Model, these three particles should behave like differently sized but otherwise identical triplets. But three experiments have produced growing evidence—including results announced in just the last few months—that the particles react differently to some as-yet mysterious influence. The findings are not yet conclusive, but if they hold up, “it would be a complete revolution,” says California Institute of Technology theorist Mark Wise.

To read more, click here.