Previously unseen 'subatomic process' detected

Two experiments at the Large Hadron Collider at the European Organization for Nuclear Research (CERN) in Geneva, Switzerland, have combined their results and observed a previously unseen subatomic process.

A joint analysis by the CMS and LHCb collaborations has established a new and extremely rare decay of the Bs particle (a heavy composite particle consisting of a bottom antiquark and a strange quark) into two muons. Theorists had predicted that this decay would only occur about four times out of a billion, and that is roughly what the two experiments observed.

Syracuse University's Sheldon Stone said that it's amazing that this theoretical prediction is so accurate and even more amazing that they can actually observe it at all, adding that this is a great triumph for the LHC and both experiments.

Fermilab's Joel Butler of the CMS experiment said that this new result allows them to discount or severely limit the parameters of most of these theories. Any viable theory must predict a change small enough to be accommodated by the remaining uncertainty.

Researchers at the LHC are particularly interested in particles containing bottom quarks because they are easy to detect, abundantly produced and have a relatively long lifespan, according to Stone.

Researchers also know that Bs mesons oscillate between their matter and their antimatter counterparts, a process first discovered at Fermilab in 2006, Stone said, adding that studying the properties of B mesons will help them understand the imbalance of matter and antimatter in the universe.

That imbalance is a mystery scientists are working to unravel. The big bang that created the universe should have resulted in equal amounts of matter and antimatter, annihilating each other on contact, but matter prevails, and scientists have not yet discovered the mechanism that made that possible.

The study is published in the journal Nature.