Scientists cataloguing the disintegration of an ethereal particle may have spotted new signs of a subtle discrepancy in the Standard Model—the theory that wraps up all of particle physics in a single equation.

The new measurement, performed at the Large Hadron Collider beauty experiment (LHCb) and led by a team at UMD, adds to a growing body of evidence that appears to contradict a basic property of the Standard Model. That property, called lepton flavor universality, seems to emerge directly from the underlying mathematics, and it imposes a democratic order on three fundamental particles: Electrons, together with their heavier cousins —the muon and the tau, should behave identically during certain kinds of particle interactions.

But for several years physicists have been finding cracks in this egalitarian image. The latest result, which makes detailed use of the different ways that very rare particles decay, strengthens the case against lepton universality and may point the way toward new physics. As more rare decays are recorded, researchers could begin to mount an even stronger case and investigate other aspects of the violation.

The paper has been accepted for publication in Physical Review Letters, and a preprint is available for download on the arXiv. The CERN Courier highlighted the result this past October.

The UMD team that devised and led the measurement includes Professor Hassan Jawahery, graduate student Jack Wimberley and postdoctoral researcher Brian Hamilton.