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67-733: [REDACTED] Look up tweedle in Wiktionary, the free dictionary. Tweedle may refer to: Scientific slang for a preon in particle physics. Tweedles (album) , by The Residents 2006 Elizabeth Tweedle (born 1985), retired British artistic gymnast Stanley H. Tweedle , major character in sci-fi TV series Lexx Tweedle, a Single-Element monster in My Singing Monsters See also [ edit ] Tweedledum and Tweedledee Tweedle Dee, Tweedle Dum (disambiguation) Tweedle Dee (disambiguation) Topics referred to by

134-422: A virtual particle ) is also used as force carrier to model the nuclear force in atomic nuclei (between protons and neutrons ). This is an approximation, as the actual carrier of the strong force is believed to be the gluon , which is explicitly used to model strong interaction between quarks. Other mesons, such as the virtual rho mesons are used to model this force as well, but to a lesser extent. Following

201-410: A 1981 paper by Fritzsch and Mandelbaum, and a 1992 book by D'Souza and Kalman. None of these have gained wide acceptance in the physics world. However, in a recent work de Souza has shown that his model describes well all weak decays of hadrons according to selection rules dictated by a quantum number derived from his compositeness model. In his model leptons are elementary particles and each quark

268-423: A box smaller than Δ ⁡ x {\displaystyle \operatorname {\Delta } x} would have a momentum uncertainty proportionally greater. Thus, the preon model proposed particles smaller than the elementary particles they make up, since the momentum uncertainty Δ ⁡ p {\displaystyle \operatorname {\Delta } p} should be greater than

335-421: A corresponding antiparticle (antimeson) in which quarks are replaced by their corresponding antiquarks and vice versa. For example, a positive pion ( π ) is made of one up quark and one down antiquark; and its corresponding antiparticle, the negative pion ( π ), is made of one up antiquark and one down quark. Because mesons are composed of quarks, they participate in both

402-617: A handful of other particles. The particles being seen in the ever-more-powerful accelerators were, according to the theory, typically nothing more than combinations of these quarks. Within the Standard Model, there are several classes of particles . One of these, the quarks , has six types, of which there are three varieties in each (dubbed " colors ", red, green, and blue, giving rise to quantum chromodynamics ). Additionally, there are six different types of what are known as leptons . Of these six leptons, there are three charged particles :

469-490: A largely ad-hoc system of hierarchies, not entirely unlike the way taxonomy grouped animals based on their physical features. Not surprisingly, the huge number of particles was referred to as the " particle zoo ". The Standard Model, which is now the prevailing model of particle physics, dramatically simplified this picture by showing that most of the observed particles were mesons , which are combinations of two quarks , or baryons which are combinations of three quarks, plus

536-512: A more fundamental level of (at first) just three quarks , consequently reducing the huge number of arbitrary constants in mid-twentieth-century particle physics prior to the Standard Model and quantum chromodynamics . However, the particular preon model discussed below has attracted comparatively little interest among the particle physics community to date, in part because no evidence has been obtained so far in collider experiments to show that

603-570: A preon (of whatever mass) confined to a box of this size is about 200 GeV/c, which is 50,000 times larger than the (model dependent) rest mass of an up-quark, and 400,000 times larger than the rest mass of an electron. Heisenberg's uncertainty principle states that Δ ⁡ x ⋅ Δ ⁡ p ≥ 1 2 ℏ {\displaystyle \operatorname {\Delta } x\cdot \operatorname {\Delta } p\geq {\tfrac {1}{2}}\hbar } and thus anything confined to

670-522: A proton placed in the same field because of its lighter mass), and the symmetry is said to be broken . It was noted that charge ( Q ) was related to the isospin projection ( I 3 ), the baryon number ( B ) and flavour quantum numbers ( S , C , B ′ , T ) by the Gell-Mann–Nishijima formula : where S , C , B ′ , and T represent the strangeness , charm , bottomness and topness flavour quantum numbers respectively. They are related to

737-414: A same total number of up and down quarks and antiquarks. Under the isospin model, they were considered a single particle in different charged states. After the quark model was adopted, physicists noted that the isospin projections were related to the up and down quark content of particles by the relation where the n -symbols are the count of up and down quarks and antiquarks. In the "isospin picture",

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804-641: Is a vector quantity that represents the "intrinsic" angular momentum of a particle. It comes in increments of ⁠ 1 / 2 ⁠   ħ . Quarks are fermions —specifically in this case, particles having spin ⁠ 1 / 2 ⁠ ( S = ⁠ 1 / 2 ⁠ ). Because spin projections vary in increments of 1 (that is 1  ħ ), a single quark has a spin vector of length ⁠ 1 / 2 ⁠ , and has two spin projections, either ( S z = + ⁠ 1 / 2 ⁠ or S z = ⁠− + 1 / 2 ⁠ ). Two quarks can have their spins aligned, in which case

871-576: Is about 0.6 times the size of a proton or neutron . All mesons are unstable, with the longest-lived lasting for only a few tenths of a nanosecond. Heavier mesons decay to lighter mesons and ultimately to stable electrons , neutrinos and photons . Outside the nucleus, mesons appear in nature only as short-lived products of very high-energy collisions between particles made of quarks, such as cosmic rays (high-energy protons and neutrons) and baryonic matter . Mesons are routinely produced artificially in cyclotrons or other particle accelerators in

938-412: Is an active area of research in meson spectroscopy . P -parity is left-right parity, or spatial parity, and was the first of several "parities" discovered, and so is often called just "parity" . If the universe were reflected in a mirror, most laws of physics would be identical—things would behave the same way regardless of what we call "left" and what we call "right". This concept of mirror reflection

1005-591: Is another quantity of quantized angular momentum , called the orbital angular momentum (quantum number L ), that is the angular momentum due to quarks orbiting each other, and also comes in increments of 1  ħ . The total angular momentum (quantum number J ) of a particle is the combination of the two intrinsic angular momentums (spin) and the orbital angular momentum. It can take any value from J = | L − S | up to J = | L + S | , in increments of 1. Particle physicists are most interested in mesons with no orbital angular momentum ( L  = 0), therefore

1072-414: Is called parity ( P ). Gravity , the electromagnetic force , and the strong interaction all behave in the same way regardless of whether or not the universe is reflected in a mirror, and thus are said to conserve parity ( P -symmetry). However, the weak interaction does distinguish "left" from "right", a phenomenon called parity violation ( P -violation). Based on this, one might think that, if

1139-485: Is composed of two primons , and thus, all quarks are described by four primons . Therefore, there is no need for the Standard Model Higgs boson and each quark mass is derived from the interaction between each pair of primons by means of three Higgs-like bosons. In his 1989 Nobel Prize acceptance lecture, Hans Dehmelt described a most fundamental elementary particle, with definable properties, which he called

1206-458: Is different from Wikidata All article disambiguation pages All disambiguation pages Preon In the hadronic sector, some effects are considered anomalies within the Standard Model. For example, the proton spin puzzle , the EMC effect , the distributions of electric charges inside the nucleons , as found by Robert Hofstadter in 1956, and the ad hoc CKM matrix elements. When

1273-516: Is electrically neutral, or Vohu which means "void"). All leptons and all flavours of quarks are three-rishon ordered triplets. These groups of three rishons have spin-½ . The Rishon model illustrates some of the typical efforts in the field. Many of the preon models theorize that the apparent imbalance of matter and antimatter in the universe is in fact illusory, with large quantities of preon-level antimatter confined within more complex structures. One preon model started as an internal paper at

1340-478: Is less massive than the lightest group of baryons, meaning that they are more easily produced in experiments, and thus exhibit certain higher-energy phenomena more readily than do baryons. But mesons can be quite massive: for example, the J/Psi meson ( J/ψ ) containing the charm quark , first seen 1974, is about three times as massive as a proton, and the upsilon meson ( ϒ ) containing

1407-449: Is upgraded to higher energies. Meson In particle physics , a meson ( / ˈ m iː z ɒ n , ˈ m ɛ z ɒ n / ) is a type of hadronic subatomic particle composed of an equal number of quarks and antiquarks , usually one of each, bound together by the strong interaction . Because mesons are composed of quark subparticles, they have a meaningful physical size, a diameter of roughly one femtometre (10  m), which

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1474-497: The cosmon , as the likely result of a long but finite chain of increasingly more elementary particles. Many preon models either do not account for the Higgs boson or rule it out, and propose that electro-weak symmetry is broken not by a scalar Higgs field but by composite preons. For example, Fredriksson preon theory does not need the Higgs boson, and explains the electro-weak breaking as

1541-748: The Particle Data Group , and are rather convoluted. The rules are presented below, in table form for simplicity. Mesons are classified into types according to their spin configurations. Some specific configurations are given special names based on the mathematical properties of their spin configuration. Flavourless mesons are mesons made of pair of quark and antiquarks of the same flavour (all their flavour quantum numbers are zero: S = 0, C = 0, B ′ = 0, T = 0). The rules for flavourless mesons are: Flavoured mesons are mesons made of pair of quark and antiquarks of different flavours. The rules are simpler in this case: The main symbol depends on

1608-583: The University of Bristol in England , based on photographic films placed in the Andes mountains. Some of those mesons had about the same mass as the already-known mu "meson", yet seemed to decay into it, leading physicist Robert Marshak to hypothesize in 1947 that it was actually a new and different meson. Over the next few years, more experiments showed that the pion was indeed involved in strong interactions. The pion (as

1675-448: The University of Munich ). Heisenberg pointed out that there is no "tr" in the Greek word "mesos". The first candidate for Yukawa's meson, in modern terminology known as the muon , was discovered in 1936 by Carl David Anderson and others in the decay products of cosmic ray interactions. The "mu meson" had about the right mass to be Yukawa's carrier of the strong nuclear force, but over

1742-443: The bottom quark , first seen in 1977, is about ten times as massive as a proton. From theoretical considerations, in 1934 Hideki Yukawa predicted the existence and the approximate mass of the "meson" as the carrier of the nuclear force that holds atomic nuclei together. If there were no nuclear force, all nuclei with two or more protons would fly apart due to electromagnetic repulsion. Yukawa called his carrier particle

1809-523: The electron , muon , and tau . The neutrinos comprise the other three leptons, and each neutrino pairs with one of the three charged leptons. In the Standard Model, there are also bosons , including the photons and gluons ; W , W , and Z bosons ; and the Higgs boson ; and an open space left for the graviton . Almost all of these particles come in "left-handed" and "right-handed" versions (see chirality ). The quarks, leptons, and W boson all have antiparticles with opposite electric charge (or in

1876-584: The wavefunction for each particle (more precisely, the quantum field for each particle type) were simultaneously mirror-reversed, then the new set of wavefunctions would perfectly satisfy the laws of physics (apart from the weak interaction). It turns out that this is not quite true: In order for the equations to be satisfied, the wavefunctions of certain types of particles have to be multiplied by −1, in addition to being mirror-reversed. Such particle types are said to have negative or odd parity ( P  = −1, or alternatively P  = −), whereas

1943-525: The weak interaction and strong interaction . Mesons with net electric charge also participate in the electromagnetic interaction . Mesons are classified according to their quark content, total angular momentum , parity and various other properties, such as C-parity and G-parity . Although no meson is stable, those of lower mass are nonetheless more stable than the more massive, and hence are easier to observe and study in particle accelerators or in cosmic ray experiments. The lightest group of mesons

2010-482: The Collider Detector at Fermilab (CDF) around 1994. The paper was written after an unexpected and inexplicable excess of jets with energies above 200  GeV were detected in the 1992–1993 running period. However, scattering experiments have shown that quarks and leptons are "point like" down to distance scales of less than 10  m (or 1 ⁄ 1000 of a proton diameter). The momentum uncertainty of

2077-599: The Standard Model) include prequarks , subquarks , maons , alphons , quinks , rishons , tweedles , helons , haplons , Y-particles , and primons . Preon is the leading name in the physics community. Efforts to develop a substructure date at least as far back as 1974 with a paper by Pati and Salam in Physical Review . Other attempts include a 1977 paper by Terazawa, Chikashige, and Akama, similar, but independent, 1979 papers by Ne'eman, Harari, and Shupe,

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2144-455: The case of the neutrinos, opposite weak isospin ). The Standard Model also has a number of problems which have not been entirely solved. In particular, no successful theory of gravitation based on a particle theory has yet been proposed. Although the Model assumes the existence of a graviton, all attempts to produce a consistent theory based on them have failed. Kalman asserts that, according to

2211-551: The collisions of protons, antiprotons , or other particles. Higher-energy (more massive) mesons were created momentarily in the Big Bang , but are not thought to play a role in nature today. However, such heavy mesons are regularly created in particle accelerator experiments that explore the nature of the heavier quarks that compose the heavier mesons. Mesons are part of the hadron particle family, which are defined simply as particles composed of two or more quarks. The other members of

2278-424: The concept of atomism , fundamental building blocks of nature are indivisible bits of matter that are ungenerated and indestructible. Neither leptons nor quarks are truly indestructible, since some leptons can decay into other leptons, some quarks into other quarks. Thus, on fundamental grounds, quarks are not themselves fundamental building blocks, but must be composed of other, fundamental quantities—preons. Although

2345-483: The course of the next decade, it became evident that it was not the right particle. It was eventually found that the "mu meson" did not participate in the strong nuclear interaction at all, but rather behaved like a heavy version of the electron , and was eventually classed as a lepton like the electron, rather than a meson. Physicists in making this choice decided that properties other than particle mass should control their classification. There were years of delays in

2412-481: The discovery of the pion, Yukawa was awarded the 1949 Nobel Prize in Physics for his predictions. For a while in the past, the word meson was sometimes used to mean any force carrier, such as "the Z meson" , which is involved in mediating the weak interaction . However, this use has fallen out of favor, and mesons are now defined as particles composed of pairs of quarks and antiquarks. Spin (quantum number S )

2479-447: The fermions of the Standard Model are composite. A number of physicists have attempted to develop a theory of "pre-quarks" (from which the name preon derives) in an effort to justify theoretically the many parts of the Standard Model that are known only through experimental data. Other names which have been used for these proposed fundamental particles (or particles intermediate between the most fundamental particles and those observed in

2546-521: The hadron family are the baryons : subatomic particles composed of odd numbers of valence quarks (at least three), and some experiments show evidence of exotic mesons , which do not have the conventional valence quark content of two quarks (one quark and one antiquark), but four or more. Because quarks have a spin ⁠ 1 / 2 ⁠ , the difference in quark number between mesons and baryons results in conventional two-quark mesons being bosons , whereas baryons are fermions . Each type of meson has

2613-409: The heavier quark, the superscript depends on the charge, and the subscript (if any) depends on the lighter quark. In table form, they are: There is experimental evidence for particles that are hadrons (i.e., are composed of quarks) and are color-neutral with zero baryon number, and thus by conventional definition are mesons. Yet, these particles do not consist of a single quark/antiquark pair, as all

2680-578: The high altitude mountainous regions of Darjeeling , and observed long curved ionizing tracks that appeared to be different from the tracks of alpha particles or protons. In a series of articles published in Nature , they identified a cosmic particle having an average mass close to 200 times the mass of electron. This discovery was made in 1947 with improved full-tone photographic emulsion plates, by Cecil Powell , Hugh Muirhead , César Lattes , and Giuseppe Occhialini , who were investigating cosmic ray products at

2747-485: The hypothetical basic particle constituents. Preon theory is motivated by a desire to replicate in particle physics the achievements of the periodic table in Chemistry, which reduced 94 naturally occurring elements to combinations of just three building-blocks (proton, neutron, electron). Likewise, the Standard Model later organized the "particle zoo" of hadrons by reducing several dozen particles to combinations at

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2814-462: The intrinsic parity of a meson is the product of the intrinsic parities of the quark (+1) and antiquark (−1). As these are different, their product is −1, and so it contributes the "+1" that appears in the exponent. As a consequence, all mesons with no orbital angular momentum ( L  = 0) have odd parity ( P  = −1). C -parity is only defined for mesons that are their own antiparticle (i.e. neutral mesons). It represents whether or not

2881-419: The isospin projections I 3 = +1 , I 3 = 0 , and I 3 = −1 respectively. This belief lasted until Murray Gell-Mann proposed the quark model in 1964 (containing originally only the u , d , and s quarks). The success of the isospin model is now understood to be an artifact of the similar masses of the u and d quarks. Because the u and d quarks have similar masses, particles made of

2948-458: The mass of each successive particle follows certain patterns, predictions of the rest mass of most particles cannot be made precisely, except for the masses of almost all baryons which have been modeled well by de Souza (2010). The Standard Model also has problems predicting the large scale structure of the universe. For instance, the SM generally predicts equal amounts of matter and antimatter in

3015-410: The meson is " G odd" ( G  = −1). The concept of isospin was first proposed by Werner Heisenberg in 1932 to explain the similarities between protons and neutrons under the strong interaction . Although they had different electric charges, their masses were so similar that physicists believed that they were actually the same particle. The different electric charges were explained as being

3082-469: The meson, from μέσος mesos , the Greek word for "intermediate", because its predicted mass was between that of the electron and that of the proton, which has about 1,836 times the mass of the electron. Yukawa or Carl David Anderson , who discovered the muon , had originally named the particle the "mesotron", but he was corrected by the physicist Werner Heisenberg (whose father was a professor of Greek at

3149-452: The nonets made of one u, one d and one other quark and breaks down for the other nonets (for example ucb nonet). If the quarks all had the same mass, their behaviour would be called symmetric , because they would all behave in exactly the same way with respect to the strong interaction. However, as quarks do not have the same mass, they do not interact in the same way (exactly like an electron placed in an electric field will accelerate more than

3216-515: The number of strange, charm, bottom, and top quarks and antiquark according to the relations: meaning that the Gell-Mann–Nishijima formula is equivalent to the expression of charge in terms of quark content: Mesons are classified into groups according to their isospin ( I ), total angular momentum ( J ), parity ( P ), G-parity ( G ) or C-parity ( C ) when applicable, and quark (q) content. The rules for classification are defined by

3283-519: The observed properties of elementary particles, which may have implications in conflict with observation. For example, now that the LHC 's observation of a Higgs boson is confirmed, the observation contradicts the predictions of many preon models that excluded it. Preon theories require quarks and leptons to have a finite size. It is possible that the Large Hadron Collider will observe this after it

3350-512: The other conventional mesons discussed above do. A tentative category for these particles is exotic mesons . There are at least five exotic meson resonances that have been experimentally confirmed to exist by two or more independent experiments. The most statistically significant of these is the Z(4430) , discovered by the Belle experiment in 2007 and confirmed by LHCb in 2014. It is a candidate for being

3417-499: The other particles are said to have positive or even parity ( P  = +1, or alternatively P  = +). For mesons, parity is related to the orbital angular momentum by the relation: where the L is a result of the parity of the corresponding spherical harmonic of the wavefunction . The "+1" comes from the fact that, according to the Dirac equation , a quark and an antiquark have opposite intrinsic parities. Therefore,

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3484-433: The particles themselves. So the preon model represents a mass paradox: How could quarks or electrons be made of smaller particles that would have many orders of magnitude greater mass-energies arising from their enormous momenta? One way of resolving this paradox is to postulate a large binding force between preons that cancels their mass-energies. Preon models propose additional unobserved forces or dynamics to account for

3551-585: The preon models try to explain the Standard Model, often predicting small discrepancies with this model and generating new particles and certain phenomena which do not belong to the Standard Model. Preon research is motivated by the desire to: Before the Standard Model was developed in the 1970s (the key elements of the Standard Model known as quarks were proposed by Murray Gell-Mann and George Zweig in 1964), physicists observed hundreds of different kinds of particles in particle accelerators . These were organized into relationships on their physical properties in

3618-871: The rearrangement of preons, rather than a Higgs-mediated field. In fact, the Fredriksson preon model and the de Souza model predict that the Standard Model Higgs boson does not exist. The rishon model (RM) is the earliest effort (1979) to develop a preon model to explain the phenomenon appearing in the Standard Model (SM) of particle physics . It was first developed by Haim Harari and Michael A. Shupe (independently of each other), and later expanded by Harari and his then-student Nathan Seiberg . The model has two kinds of fundamental particles called rishons (ראשונים) (which means "First" in Hebrew ). They are T ("Third" since it has an electric charge of ⅓  e , or Tohu (תוהו) which means "Chaos" ) and V ("Vanishes", since it

3685-485: The result of some unknown excitation similar to spin. This unknown excitation was later dubbed isospin by Eugene Wigner in 1937. When the first mesons were discovered, they too were seen through the eyes of isospin and so the three pions were believed to be the same particle, but in different isospin states. The mathematics of isospin was modeled after the mathematics of spin . Isospin projections varied in increments of 1 just like those of spin, and to each projection

3752-400: The same number of them also have similar masses. The exact u and d quark composition determines the charge, because u quarks carry charge ⁠+ + 2 / 3 ⁠ whereas d quarks carry charge ⁠− + 1 / 3 ⁠ . For example, the three pions all have different charges but they all have similar masses ( c. 140 MeV/ c ) as they are each composed of

3819-411: The same term [REDACTED] This disambiguation page lists articles associated with the title Tweedle . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Tweedle&oldid=1241098642 " Category : Disambiguation pages Hidden categories: Short description

3886-503: The subatomic particle research during World War II (1939–1945), with most physicists working in applied projects for wartime necessities. When the war ended in August ;1945, many physicists gradually returned to peacetime research. The first true meson to be discovered was what would later be called the "pi meson" (or pion). During 1939–1942, Debendra Mohan Bose and Bibha Chowdhuri exposed Ilford half-tone photographic plates in

3953-444: The term "preon" was coined, it was primarily to explain the two families of spin- ⁠ 1 / 2 ⁠ fermions: quarks and leptons. More recent preon models also account for spin-1 bosons, and are still called "preons". Each of the preon models postulates a set of fewer fundamental particles than those of the Standard Model, together with the rules governing how those fundamental particles combine and interact. Based on these rules,

4020-785: The three pions and three rhos were thought to be the different states of two particles. However, in the quark model, the rhos are excited states of pions. Isospin, although conveying an inaccurate picture of things, is still used to classify hadrons, leading to unnatural and often confusing nomenclature. Because mesons are hadrons, the isospin classification is also used for them all, with the quantum number calculated by adding I 3 = + ⁠ 1 / 2 ⁠ for each positively charged up-or-down quark-or-antiquark (up quarks and down antiquarks), and I 3 = − ⁠ 1 / 2 ⁠ for each negatively charged up-or-down quark-or-antiquark (up antiquarks and down quarks). The strangeness quantum number S (not to be confused with spin)

4087-443: The two groups of mesons most studied are the S  = 1; L  = 0 and S  = 0; L  = 0, which corresponds to J  = 1 and J  = 0, although they are not the only ones. It is also possible to obtain J  = 1 particles from S  = 0 and L  = 1. How to distinguish between the S  = 1, L  = 0 and S  = 0, L  = 1 mesons

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4154-646: The two spin vectors add to make a vector of length S = 1 , with three possible spin projections ( S z = +1, S z = 0, and S z = −1), and their combination is called a vector meson or spin-1 triplet. If two quarks have oppositely aligned spins, the spin vectors add up to make a vector of length S = 0, and only one spin projection ( S z = 0 ), called a scalar meson or spin-0 singlet. Because mesons are made of one quark and one antiquark, they are found in triplet and singlet spin states. The latter are called scalar mesons or pseudoscalar mesons , depending on their parity (see below). There

4221-459: The universe. A number of attempts have been made to "fix" this through a variety of mechanisms, but to date none have won widespread support. Likewise, basic adaptations of the Model suggest the presence of proton decay , which has not yet been observed. Several models have been proposed in an attempt to provide a more fundamental explanation of the results in experimental and theoretical particle physics, using names such as " parton " or "preon" for

4288-401: The wavefunction of the meson remains the same under the interchange of their quark with their antiquark. If then, the meson is " C even" ( C  = +1). On the other hand, if then the meson is " C odd" ( C  = −1). C -parity rarely is studied on its own, but more commonly in combination with P-parity into CP-parity . CP -parity was originally thought to be conserved, but

4355-527: Was associated a " charged state ". Because the "pion particle" had three "charged states", it was said to be of isospin I = 1 . Its "charged states" π , π , and π , corresponded to the isospin projections I 3 = +1 , I 3 = 0 , and I 3 = −1 respectively. Another example is the " rho particle ", also with three charged states. Its "charged states" ρ , ρ , and ρ , corresponded to

4422-419: Was later found to be violated on rare occasions in weak interactions . G -parity is a generalization of the C -parity. Instead of simply comparing the wavefunction after exchanging quarks and antiquarks, it compares the wavefunction after exchanging the meson for the corresponding antimeson, regardless of quark content. If then, the meson is " G even" ( G  = +1). On the other hand, if then

4489-535: Was noticed to go up and down along with particle mass. The higher the mass, the lower (more negative) the strangeness (the more s quarks). Particles could be described with isospin projections (related to charge) and strangeness (mass) (see the uds nonet figures). As other quarks were discovered, new quantum numbers were made to have similar description of udc and udb nonets. Because only the u and d mass are similar, this description of particle mass and charge in terms of isospin and flavour quantum numbers only works well for

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