From my old stomping grounds of Fermilab, about an hour outside Chicago and Evanston, comes measurements of muon magnetic properties that deviate significantly from the Standard Model, the theory we have that explains everything we know about the particles and forces of Nature, with the exception of gravity.
Muons are in the electron family (200 times more massive...a heavy electron, basically, but it also decays with a lifetime of around 2.2 microseconds), and therefore 'spin' like the electron does. When you put spinning charged particles in a magnetic field, they precess...like a spinning top does if it is slightly tilted while spinning, and its whole axis rotates in a cone shape. By measuring these gyrations of muons as they spin in magnetic fields, precise measurements of their behavior are made. And these behaviors differ from what is predicted in the Standard Model. Some of the only theoretical explanations for such a difference involves new types of particles/matter.
Check out this article if interested. This is also a good example of how discovery claims need to hold up to standards in a field built around error analysis! There needs to be a large enough gap between the predicted and lab results, but also a large enough gap between their error bars, of 5 sigma (5 standard deviations). The experiments still need more data to shrink these error bars a little smaller before they can claim discovery of some new physics, but it is getting close, and therefore more and more convincing that something new is out there!!
