A lambda hyperon decays into a proton, electron, and an invisible antineutrino, providing the information needed for physicists to examine the CKM matrix. Credit: The BESIII Collaboration
Physicists at the BESIII Collaboration have breathed new life into a decades-old test of one of the Standard Model's most important ideas, using a technique that had gone almost untouched by experimenters for 35 years.
In new research published in Nature, the researchers examined a small table of numbers called the CKM matrix, which governs how one type of fundamental particle can transform into another. By tracking pairs of unstable particles called lambda hyperons, linked through quantum entanglement, the team produced a fresh, independent measurement that lines up with what the Standard Model predicts.
Switching flavors
To date, the Standard Model is physicists' best working theory of the particles that make up matter and the forces that govern them. All hadronic matter is made up of quarks, which come in six types, or "flavors": up, down, strange, charm, top and bottom.
