A slide from the July 4 presentation. The search with the purest expected signal is done by examining events with two Z bosons that have decayed to pairs of electrons. CERN said that in the region from 120 to 130 GeV, 13 events are seen where only 5.3 were expected. Here's where probability comes in. Scientists say that the likelihood of such an excess would be three times in ten thousand if there were no new particle, according to CERN.