GENEVA - After a quarter-century of searching, scientists have nailed down how one particularly rare subatomic particle decays into something else - a discovery that adds certainty to our thinking about how the universe began and keeps running.
The world's top particle physics lab said Friday it had measured the decay time of a particle known as a Bs (B sub s) meson into two other fundamental particles called muons, which are much heavier than but similar to electrons. It was observed as part of the reams of data coming from CERN's $10 billion Large Hadron Collider, the world's largest atom smasher, on the Swiss-French border near Geneva.
The rare sighting at the European Center for Nuclear Research, known by its French acronym CERN, shows that the so-called standard model of particle physics is "coming through with flying colors," though it describes only 5 percent of the universe, said Pierluigi Campana, who leads one of the two main teams at CERN involved in the research.
Campana called the results an important development that helps confirm the standard model, a theory developed over the past half century to explain the basic building blocks of matter.
It applies to everything from galaxies and stars to the smallest microcosms, showing how they are thought to have come into being and continue to function. The results were formally unveiled at a major physics conference in Stockholm.
Also at the conference, an international team of scientists based at Japan's Proton Accelerator Research Complex announced they have documented muon neutrinos transforming into electron neutrinos - a previously unknown third way that neutrinos can spontaneously change identity. Neutrinos are subatomic particles that are very hard to detect because they have extremely low mass and rarely interact with matter.
That breakthrough is "a big deal," said one of the neutrino collaboration leaders, University of California-Irvine physicist Henry Sobel, because explaining the matter-antimatter asymmetry in neutrinos may shed light on why everything from tiny forms of life to stars are made of matter, but there is almost no antimatter left in the universe. That remains one of the biggest mysteries of the universe - since the Big Bang nearly 14 billion years ago should have created equal amounts of matter and antimatter.
The standard model also predicted a new subatomic particle discovered last summer - the long-sought Higgs boson.