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           Although many people may know of matter (anything having mass and volume), few understand what comprises it. A matter component is a quark, any part of a group of subatomic particles classified by their strong force-based interactions. The strong force is one of the four fundamental interactions of nature that interact with subatomic particles of matter. The strong force can bind quarks to create better-known subatomic particles, such as protons and neutrons. Quarks are truly elementary particles, meaning they don’t have an apparent structure and cannot get broken down further. They occur only when joined with other quarks, antiquarks, and antiparticles. Other quarks have 6 types (also called quark “flavors”), which include up, down, charm, strange, top, and bottom quarks.
           In 1964, Murray Gell-Mann and George Zweig discovered the up, down, and strange quarks. The up and down quarks are not only the most common but the smallest in size compared to the other quarks. Up and down quarks are the most common due to being an irreplaceable component of protons and neutrons, meaning they comprise most ordinary matter. The up quark has a ⅔e charge and is the lightest quark at about 2-8 MeV (mega electron volt).  The down quark has -⅓e charge and is the 2nd lightest quark at about 5-15 MeV. Unlike the up and down quarks, strange quarks are found as components of K mesons and were discovered in observation of cosmic ray interaction in 1947. Mesons are a group of subatomic particles formed by a pairing of quarks and matching antiquarks. Strange quarks also have no part in ordinary matter, unlike up and down quarks. The strange quark is the 3rd lightest quark at about 100-300 MeV.

             The other three quarks (charm, top, and bottom) were discovered in the 1970s. The charm quark was discovered in 1974 by Burton Richter and Samuel Ting. Both shared the Nobel Prize in 1976 for their discovery. It was discovered with a meson called the J/Psi particle, an interaction between the charm quark and its antiquark, called the anti charm quark. This discovery led many researchers to believe that quarks form in pairs. It is also the 3rd heaviest quark at 1,000-1,600 MeV and has a charge of ⅔e. Like the charm quark, the bottom quark was also discovered, due to another meson's discovery, that formed with the bottom quark-antiquark pairing. In 1977, Leon Lederman and his experimental group at Fermilab discovered it and the upsilon meson.  It is the 2nd heaviest quark, and it has a mass of 4,100-4,500 MeV and has a charge of-⅓e. Due to Fermilab’s discovery of the bottom quark, they also discovered the top quark later in 1995. The top quark was discovered from a collision between 0.9 TeV protons and equally energetic protons in a proton-antiproton collider. The top quark has a charge of ⅔e and is the heaviest quark at about 180,000 MeV. This makes it the largest elementary particle.


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“The Discovery of the Bottom Quark.” Bottomstory,

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