Dinosaurs came in many different shapes and sizes.
The first generation includes up and down quarks, the second strange and charm quarks, and the third bottom and top quarks. All searches for a fourth generation of quarks and other elementary fermions have failed,   and there is strong indirect evidence that no more than three generations exist.
Only first-generation up and down quarks occur commonly in nature. Heavier quarks can only be created in high-energy collisions such as in those involving cosmic raysand decay quickly; however, they are thought to have been present during the first fractions of a second after the Big Bangwhen the universe was in an extremely hot and dense phase the quark epoch.
Studies of heavier quarks are conducted in artificially created conditions, such as in particle accelerators. However, since no successful quantum theory of gravity exists, gravitation is not described by the Standard Model.
See the table of properties below for a more complete overview of the six quark flavors' properties. At the time of the quark theory's inception, the " particle zoo " included, amongst other particles, a multitude of hadrons. Gell-Mann and Zweig posited that they were not elementary particles, but were instead composed of combinations of quarks and antiquarks.
Their model involved three flavors of quarks, updownand strangeto which they ascribed properties such as spin and electric charge. There was particular contention about whether the quark was a physical entity or a mere abstraction used to explain concepts that were not fully understood at the time.
Sheldon Lee Glashow and James Bjorken predicted the existence of a fourth flavor of quark, which they called charm.
The addition was proposed because it allowed for a better description of the weak interaction the mechanism that allows quarks to decayequalized the number of known quarks with the number of known leptonsand implied a mass formula that correctly reproduced the masses of the known mesons.
Photograph of the event that led to the discovery of the c baryonat the Brookhaven National Laboratory in The strange quark's existence was indirectly validated by SLAC's scattering experiments: This theoretical model required the existence of the as-yet undiscovered charm quark.
The charm quarks were observed bound with charm antiquarks in mesons. The discovery finally convinced the physics community of the quark model's validity. Of these, the paper by Haim Harari  was the first to coin the terms top and bottom for the additional quarks.
Sure he hasn't got much of a bark And sure any he has it's all beside the mark. Since "quark" meaning, for one thing, the cry of the gull was clearly intended to rhyme with "Mark", as well as "bark" and other such words, I had to find an excuse to pronounce it as "kwork".
But the book represents the dream of a publican named Humphrey Chimpden Earwicker. Words in the text are typically drawn from several sources at once, like the " portmanteau " words in Through the Looking-Glass. From time to time, phrases occur in the book that are partially determined by calls for drinks at the bar.
I argued, therefore, that perhaps one of the multiple sources of the cry "Three quarks for Muster Mark" might be "Three quarts for Mister Mark", in which case the pronunciation "kwork" would not be totally unjustified.
In any case, the number three fitted perfectly the way quarks occur in nature. Zweig preferred the name ace for the particle he had theorized, but Gell-Mann's terminology came to prominence once the quark model had been commonly accepted.
The up and down quarks are named after the up and down components of isospinwhich they carry.Why is it called stabilized aqueous ozone? Because tap water around the world contains varying types and amounts of minerals in the water. These minerals affect the performance of aqueous ozone.
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