Quark meaning
However, confinement makes it impossible to measure these properties of quarks. Usually these properties are directly determined by experiments. These new phases of QCD matter have been predicted theoretically, and experimental searches for them have now started.Įvery subatomic particle is completely described by a small set of observables such as mass m and quantum numbers, such as spin S and parity P. However, it may be possible to change the confinement by creating dense or hot quark matter. Although there is no mathematical derivation of confinement in QCD, it is easy to show using lattice gauge theory.
#Quark meaning free
The absence of free quarks has therefore been incorporated into the notion of confinement, which, it is believed, the theory of quarks must possess.Ĭonfinement began as an experimental observation, and is expected to follow from the modern theory of strong interactions, called quantum chromodynamics (QCD).
#Quark meaning for free
No search for free quarks or fractional electric charges has returned convincing evidence. The word is also a pun on the relationship between Munster and its provincial capital, Cork. In Joyce's use, it is seabirds giving "three quarks", akin to three cheers, "quark" having a meaning of the cry of a gull (probably onomatopoeia, like "quack" for ducks). The phrase "three quarks" is a particularly good fit (as mentioned in the above quote), as at the time, there were only three known quarks, and since quarks appear in groups of three in baryons. In any case, the number three fitted perfectly the way quarks occur in nature. 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. From time to time, phrases occur in the book that are partially determined by calls for drinks at the bar. Words in the text are typically drawn from several sources at once, like the "portmanteau" words in "Through the Looking Glass". But the book represents the dream of a publican named Humphrey Chimpden Earwicker. 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". Then, in one of my occasional perusals of Finnegans Wake, by James Joyce, I came across the word "quark" in the phrase "Three quarks for Muster Mark". Gell-Mann's own explanation: In 1963, when I assigned the name "quark" to the fundamental constituents of the nucleon, I had the sound first, without the spelling, which could have been "kwork". In this context, the word rhymes with "mark", and "bark", but the physics term is pronounced "kwork". Later, he found the word "quark" in James Joyce's book Finnegans Wake, and used the spelling but not the pronunciation:Īnd sure any he has it's all beside the mark. The word was originally coined by Murray Gell-Mann as a nonsense word rhyming with "pork", but without a spelling. This is a direct consequence of confinement. Isolated quarks are never found naturally they are almost always found in groups of two ( mesons) or groups of three ( baryons) called hadrons. Quarks are the only fundamental particles that interact through all four of the fundamental forces.Īntiparticles of quarks are called antiquarks. It is this which makes the difference when quarks clump together to form protons or neutrons: a proton is made up of two up quarks and one down quark, yielding a net charge of +1 while a neutron contains one up quark and two down quarks, yielding a net charge of 0. (Their names were chosen arbitrarily based on the need to name them something that could be easily remembered and used.) The up and down varieties survive in profusion, and are distinguished by (among other things) their electric charge. There are six different types of quark, usually known as flavors: up, down, charm, strange, top, and bottom. Various species of quarks combine in specific ways to form protons and neutrons, in each case taking exactly three quarks to make the composite particle in question. A quark ( IPA: /kwɔrk/) is a generic type of physical particle that forms one of the two basic constituents of matter, the other being the lepton.