Data from the Large Hadron Collider (LHC) outside Geneva appears to have proved the existence of particles made of five quarks, solving a 50-year-old puzzle about the building blocks of matter, scientists said on Tuesday.
Quarks are the tiny ingredients of subatomic particles such as protons and neutrons, which are made of three quarks. The less common and more unstable mesons, particles found in cosmic rays, have four.
A five-quark version, or "pentaquark," has been sought, but never found, ever since Murray Gell-Mann and George Zweig theorized the existence of such sub-atomic particles in 1964.