Physicists from the NA62 Collaboration at CERN reported today that they had observed a candidate event of an extremely rare charged kaon decay (K+ → π+νν–). NA62 experiment in CERN’s North Area. Image credit: NA62 / CERN. What if the odds of an event occurring were about one in ten billion? This is the case for the decay of a positively charged particle known as a kaon into another positively charged particle called a pion and a neutrino-antineutrino...