The Large Hadron Collider Beauty (LHCb) project at CERN today announced the discovery of an exotic hadron that was previously theorized but never confirmed until now. The LHCb project is a collaborative scientific effort in high energy physics that seeks to investigate how matter and energy were formed after the Big Bang fourteen billion years ago.
Hadrons are subatomic particles that form parts of atoms and are bound together by a fundamental force called the nuclear strong force. Hadrons are composed of smaller subatomic particles called quarks. Protons and neutrons are kinds of hadrons that consist of three quarks called baryons, whereas another type of hadron is the meson which consists of a quark and antiquark. Until now, those were the only kinds of hadrons we knew existed; others were theorized but never confirmed to exist until today.
An exotic hadron is a hadron that does not conform to the baryon and meson models. The quark content of exotic hadrons can be four quarks or more, and scientists have attempted to find evidence of the existence of these exotic hadrons for over 50 years. The closest they have come to the discovery was during a scientific collaboration in 2008 called the Belle experiment, where exotic hadron candidates were detected but not confirmed.
Today the LHCb has found evidence of an exotic hadron that doesn’t conform to the known hadron models; they have strong statistical confirmation that it is not a three quark or two quark configuration. This particle has been designated the Z(4430). They expect it is a tetraquark exotic hadron (one consisting of four quarks), and we expect to find out more soon.
Our thanks to W. Blaine Dowler for his assistance with this article.