The Science Newswise — Quarks are the basic particles that make up visible matter in the universe. The most intriguing and most puzzling property of quarks is that they are never found in isolation. Instead, they can only be observed when confined inside composite particles such as protons .
Nuclear physicists use giant particle accelerators to produce various types of quarks and study how they evolve to form observable particles. Groups of three quarks form composite particles called baryons (such as protons and neutrons ), while pairs of quarks form mesons. New measurements from the Large Hadron Collider beauty (LHCb) experiment show surprising variations in the rate at which baryons are produced, defying previous expectations.
The Impact The atomic nuclei that form all visible matter are composed of baryons (specifically, protons and neutrons), which scientists believe formed in the early universe . Baryons inside nuclei are stable particles that do not undergo radioactive decay. However, all mesons are unstable, and they rapidly decay into lighter particles that cannot form atoms.
The existence of stable baryons versus unstable mesons is therefore what makes the existence of atoms and the universe as we know it possible. The LHCb experiment has shown that the rate of quarks forming into baryons versus mesons depends greatly on the density of their environment. This finding helps to explain the creation of the first stable particles in the early universe.
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