Scientists have become convinced of the existence of a special type of decay of subatomic particles called kaons. Further study of the rare decay may reveal a potential flaw in the Standard Model, physicists’ unchanging theory of subatomic particles.

This decay is known as the “golden channel” because its rate can be predicted with high accuracy by the standard model. An experiment called NA62 is set to test this exact prediction.

“If we see discrepancies, it will definitely be a sign of new physics,” says Cristina Lazzeroni, a physicist working on the experiment.

NA62 searches for the decay of positively charged kaons by blasting high-energy protons at a target at CERN, the European particle physics laboratory near Geneva, and observing the resulting kaons and the particles they decay into. Kaons decay through the gold channel only 13 times out of 100 billion, scientists from the NA62 experiment reported on September 24 at a workshop at CERN.

That’s about 50 percent more likely than the Standard Model predicts, says Lazzeroni of the University of Birmingham in England. But given the precision of the measurements, “it’s still consistent with the standard model at this point.”

The ultra decay of a kaon produces another particle called a peony, and even two light, electrically neutral particles: the neutrino and its antimatter counterpart, the antineutrino. (The most common way a charged kaon decays is to produce a neutrino and a heavy relative of the electron called a muon.)

The preliminary result of NA62 indicated a decay corresponding to the gold channel, but this measurement did not fall under the statistical significance required to claim a discovery – five sigma.

NA62 will continue to acquire data and will make more accurate measurements in the future that will allow us to determine with greater confidence whether the Standard Model is correct. Another experiment called KOTO is working to detect another rare kaon decay.