Meson - Citizendia

*Meson*
Mesons of spin 0 form a nonet
Composition	Composite - Quarks and antiquarks
Family	Hadron
Interaction	Strong
Theorized	Hideki Yukawa (1935)
Discovered	1947
No. A nonet refers to a group of nine In music a nonet is a composition which requires nine musicians for a performance In Physics, a bound state is a composite of two or more building blocks ( particles or bodies) that behaves as a single object In Physics, a quark (kwɔrk kwɑːk or kwɑːrk is a type of Subatomic particle. to most kinds of particles, there is an associated antiparticle with the same Mass and opposite Electric charge. In Particle physics, a hadron ( from the ἁδρός hadrós, " stout, thick " ( In Physics, a fundamental interaction or fundamental force is a mechanism by which particles interact with each other and which cannot be explained in terms In particle physics the strong interaction, or strong force, or color force, holds Quarks and Gluons together to form Protons and né, was a Japanese Theoretical physicist and the first Japanese Nobel laureate. of types	~140 (List)
Spin	Integer
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Mesons of spin 1 form a nonet

In particle physics, a meson is a strongly interacting boson—that is, a hadron with integer spin. This is a list of known and predicted Mesons. Mesons are made of Quarks and as such are part of the Subatomic particle family called the Hadrons In Quantum mechanics, spin is a fundamental property of atomic nuclei, Hadrons and Elementary particles For particles with non-zero spin Particle physics is a branch of Physics that studies the elementary constituents of Matter and Radiation, and the interactions between them In particle physics the strong interaction, or strong force, or color force, holds Quarks and Gluons together to form Protons and In Particle physics, bosons are particles which obey Bose-Einstein statistics; they are named after Satyendra Nath Bose and Albert Einstein In Particle physics, a hadron ( from the ἁδρός hadrós, " stout, thick " ( In Quantum mechanics, spin is a fundamental property of atomic nuclei, Hadrons and Elementary particles For particles with non-zero spin In the Standard Model, mesons are composite (non-elementary) particles composed of an even number of quarks and antiquarks. The Standard Model of Particle physics is a theory that describes three of the four known Fundamental interactions together with the Elementary particles In Physics, a quark (kwɔrk kwɑːk or kwɑːrk is a type of Subatomic particle. to most kinds of particles, there is an associated antiparticle with the same Mass and opposite Electric charge. All known mesons are believed to consist of a quark-antiquark pair—the so-called valence quarks—plus a "sea" of virtual quark-antiquark pairs and virtual gluons. In Physics, the quark model is a classification scheme for Hadrons in terms of their valence quarks, i Gluons ( Glue and the suffix -on) are Elementary particles that cause Quarks to interact and are indirectly responsible for the Searches for exotic mesons that have different constituents are ongoing. Non- Quark model mesons include exotic mesons, which have Quantum numbers not possible for mesons in the Quark model; Glueballs The valence quarks may exist in a superposition of flavor states; for example, the neutral pion is neither an up-antiup pair nor a down-antidown pair, but an equal superposition of both. In Physics, the quark model is a classification scheme for Hadrons in terms of their valence quarks, i In Particle physics, flavour or flavor (see spelling differences) is a Quantum number of Elementary particles related to their In Particle physics, pion (short for pi meson) is the collective name for three Subatomic particles, and. Quantum superposition is the fundamental law of Quantum mechanics. Pseudoscalar mesons (spin 0), where the quark and antiquark have opposite spin, have the lowest rest energy. In High energy physics, a pseudoscalar meson is a Meson with total spin 0 and odd parity (usually noted as JP =0&minus Next lowest in rest energy are vector mesons (spin 1), where the quark and antiquark have parallel spin. In High energy physics, a vector meson is a Meson with total spin 1 and odd Parity (usually noted as JP =1&minus Both come in higher-energy versions where the spin is augmented by orbital angular momentum. In Physics, the angular momentum of a particle about an origin is a vector quantity equal to the mass of the particle multiplied by the Cross product of the position All mesons are unstable.

Mesons were originally predicted as carriers of the force that binds protons and neutrons together. The proton ( Greek πρῶτον / proton "first" is a Subatomic particle with an Electric charge of one positive This article is a discussion of neutrons in general For the specific case of a neutron found outside the nucleus see Free neutron. When first discovered, the muon was identified with this family from its similar mass and was named "mu meson". The muon (from the letter mu (μ--used to represent it is an Elementary particle with negative Electric charge and a spin of 1/2 However it did not show a strong attraction to nuclear matter and is actually a lepton. Leptons are a family of fundamental Subatomic particles comprising the Electron, the Muon, and the Tauon (or tau particle as well as their The pion was the first true meson to be discovered. (The current picture of intranuclear forces is quite complicated; see quantum hydrodynamics for a discussion of modern theories in which nucleon-nucleon interactions are mediated by meson exchange. Quantum hydrodynamics is more than the study of Superfluidity. The nuclear force (or nucleon-nucleon interaction or residual strong force) is the force between two or more Nucleons It is responsible for )

1 History
2 Naming of the mesons
- 2.1 Flavorless mesons
- 2.2 Flavored mesons
3 See also
4 External links
- 4.1 Recent Findings

History

In 1949 Hideki Yukawa was awarded the Nobel Prize in Physics for predicting the existence of the meson. né, was a Japanese Theoretical physicist and the first Japanese Nobel laureate. The Nobel Prize (Nobelpriset (Nobelprisen is a Swedish prize established in the 1895 will of Swedish chemist Alfred Nobel; it was first awarded in Peace, Literature Physics (Greek Physis - φύσις in everyday terms is the Science of Matter and its motion. He called the particle the meson, from mesos, Greek for intermediate, because its mass was between that of the electron and proton. He had originally named it the 'mesotron', but was corrected by Werner Heisenberg (whose father was a professor in Greek at the University of Munich), who pointed out that there is no 'tr' in the Greek word 'mesos'. Werner Heisenberg (5 December 1901 in Würzburg &ndash1 February 1976 in Munich) was a German theoretical physicist best known for enunciating the

Naming of the mesons

The name of a meson is devised so that its main properties can be inferred. Conversely, given a meson's properties, its name is clearly determined. The naming conventions fall in two categories based on flavor: flavorless mesons and flavored mesons. In Particle physics, flavour or flavor (see spelling differences) is a Quantum number of Elementary particles related to their

Flavorless mesons

Flavorless mesons are mesons whose flavor quantum numbers are all equal to zero. This means that these quarks are quarkonium states (quark-antiquark pairs of the same flavor) or a linear superposition of such states. In Particle physics, quarkonium (pl quarkonia) designates a flavorless Meson whose constituents are a Quark and its own antiquark

The name of a flavorless meson is determined by its total spin S and total orbital angular momentum L. In Atomic physics, the spin quantum number is a Quantum number that parameterizes the intrinsic Angular momentum (or spin angular momentum or simply The Azimuthal quantum number (or orbital angular momentum quantum number, second quantum number) symbolized as l (lower-case L is a Quantum number As a meson is composed of two quarks with s = 1/2, the total spin can only be S = 1 (parallel spins) or S = 0 (anti-parallel spins). The orbital quantum number L is due to the revolution of one quark around the other. Usually higher orbital angular momenta translate into a higher mass. These two quantum numbers determine the parity P and the charge-conjugation parity C of the meson:

P = (−1)^L+1

C = (−1)^L+S

Also, L and S add together to form a total angular momentum quantum number J, whose values range from |L−S| to L+S in one-unit steps. In Physics, C parity or charge parity is a Multiplicative quantum number of some particles that describes its behavior under a symmetry operation of See also Azimuthal quantum number#Addition of quantized angular momenta In Quantum mechanics, the total angular quantum momentum numbers parameterize the total The different possibilities are summarized with the use of the term symbol ^2S+1L_J (a letter code is used instead of the actual value of L, see the spectroscopic notation) and the symbol J^PC (here only the sign is used for P and C). In Quantum mechanics, the term symbol is an abbreviated description of the Angular momentum quantum numbers in a multi- Electron Atom. Spectroscopic notation provides various ways to specify atomic ionization states, as well as atomic and Molecular orbitals.

The different possibilities and the corresponding meson symbols are given in the following table:

	J^PC =	(0, 2…)^{− +}	(1, 3…)^{+ −}	(1,2…)^{− −}	(0, 1…)^{+ +}
Quark composition	^2S+1L_J = ^*	¹(S, D…)_J	¹(P, F…)_J	³(S, D…)_J	³(P, F…)_J
$u \bar d\mbox{, }u \bar u - d\bar d\mbox{, }d\bar u$ ^†	I = 1	π	b	ρ	a
$u \bar u + d \bar d \mbox{, }s \bar s$ ^‡	I = 0	η, η’	h, h’	$\phi\,\!$ , ω	f, f’
$c \bar c$	I = 0	η_c	h_c	ψ ^•	χ_c
$b \bar b$	I = 0	η_b	h_b	Υ ^**	χ_b

Notes:

^* Note that some combinations are forbidden: 0^{− −}, 0^{+ −}, 1^{− +}, 2^{+ −}, 3^{− +}. In Physics, and specifically Particle physics, isospin ( isotopic spin, isobaric spin) is a Quantum number related to the . .

^† First row form isospin triplets: π⁻, π⁰, π⁺ etc.

^‡ Second row contains pairs of elements: φ is supposed to be a $s\bar s$ state, and ω a $u \bar u + d \bar d$ state. In the other cases, the exact composition is not known, so a prime is used to distinguish the two forms.

^• For historical reasons, 1³S₁ form of ψ is called J/ψ

^** The bottomonium state symbol is a capital upsilon (may be rendered as a capital Y depending of the font/browser)

The normal spin-parity series is formed by those mesons where P=(−1)^J. The J/ψ is a Subatomic particle, a flavor -neutral Meson consisting of a charm Quark and a charm anti -quark In Particle physics, quarkonium (pl quarkonia) designates a flavorless Meson whose constituents are a Quark and its own antiquark In the normal series, S = 1 so PC = +1 (i. e. , P = C). This corresponds to some of the triplet states (triplet states appear in the last two columns).

Feynman diagram of one mode in which the eta particle can decay into 3 pions by gluon emission. Motivation and history When calculating Scattering cross sections in Particle physics, the interaction between particles can be described In Particle physics, pion (short for pi meson) is the collective name for three Subatomic particles, and. Gluons ( Glue and the suffix -on) are Elementary particles that cause Quarks to interact and are indirectly responsible for the

Since some of these symbols can refer to more than one particle, some extra rules are added:

In this scheme, particles with J^P = 0⁻ are known as pseudoscalars, and mesons with J^P = 1⁻ are called vectors. For particles other than those, the number J is added as a subindex: a₀, a₁, χ_c1, etc.
For most of ψ, Υ and χ states it is common to include spectroscopic information: Υ(1S), Υ(2S). The first number is the principal quantum number, and the letter is the spectroscopic notation for L. In Atomic physics, the principal quantum number symbolized as n is the first of a set of Quantum numbers (which includes the principal quantum Multiplicity is omitted since it is implied by the symbol, and J appears as a subindex when needed: χ_b2(1P). If spectroscopic information is not available, mass is used instead: Υ(9460).
The naming scheme does not differentiate between "pure" quark states and gluonium states, so gluonium states follow the same naming scheme. In Particle physics, a glueball is a strongly interacting particle containing no valence Quarks It is composed entirely of Gluons Such a state
However, exotic mesons with "forbidden" quantum numbers J^PC = 0^{− −}, 0^{+ −}, 1^{− +}, 2^{+ −}, 3^{− +}. . . would use the same convention as the meson with identical J^P numbers, but adding a J subindex. A meson with isospin 0 and J^PC = 1^{− +} would be denoted ω₁.

When the quantum numbers of a particle are unknown, it is designated with an X followed by its mass in parentheses.

Flavored mesons

For flavored mesons, the naming scheme is a little simpler.

1. The meson name is given by the heaviest of the two quarks. From more to less massive, the order is: t > b > c > s > d > u. However, u and d do not carry any flavor, so they do not influence the naming scheme. Quark t never forms hadrons, but a symbol for t-containing mesons is reserved anyway.

quark	symbol	quark	symbol
c	D	t	T
s	$\bar K$	b	$\bar B$

For s and b quarks we get an antiparticle symbol. This is because the adopted convention is that flavor charge and electric charge must agree in sign. Electric charge is a fundamental conserved property of some Subatomic particles which determines their Electromagnetic interaction. This is also true for the third component of isospin: quark up has positive I₃ and charge, quark down has negative charge and I₃. In Physics, and specifically Particle physics, isospin ( isotopic spin, isobaric spin) is a Quantum number related to the The effect of that is: any flavor of a charged meson has the same sign as the meson's electric charge.

2. If the second quark has also flavor (it is not u or d) then the identity of that second quark is given by a subindex (s, c or b, and in theory t).

3. Add a "*" superindex if the meson is in the normal spin-parity series, i. e. J^P = 0⁺, 1⁻, 2⁺. . .

4. For mesons other than pseudoscalars (0⁻) and vectors (1⁻) the total angular momentum quantum number J is added as a subindex. See also Azimuthal quantum number#Addition of quantized angular momenta In Quantum mechanics, the total angular quantum momentum numbers parameterize the total

To sum it up, we have:

quark composition	Isospin	J^P = 0⁻, 1⁺, 2⁻. . .	J^P = 0⁺, 1⁻, 2⁺. . .
$\bar su,\ \bar sd$	1/2	$K J$ ^†	$K^*_J$
$c \bar u,\ c\bar d$	1/2	$D J$	$D^*_J$
$c \bar s$	0	$D s J$	$D^*_{sJ}$
$\bar bu,\ \bar bd$	1/2	$B J$	$B^*_J$
$\bar bs$	0	$B s J$	$B^*_{sJ}$
$\bar bc$	0	$B c J$	$B^*_{cJ}$

† J is omitted for 0⁻ and 1⁻

In some cases, particles can mix between them. For example, the neutral kaon, $K^0\,(\bar sd)$ and its antiparticle $\bar K^0\,(s\bar d)$ can combine in a symmetric or antisymmetric manner, originating two new particles, the short-lived and the long-lived neutral kaons $K^0_S = \begin{matrix}{1 \over \sqrt 2}\end{matrix}(K^0-\bar K^0),\;K^0_L = \begin{matrix}{1 \over \sqrt 2}\end{matrix}(K^0 + \bar K^0)$ (neglecting a small CP-violating term). In Particle physics, CP violation is a violation of the postulated CP symmetry of the laws of physics

External links

A table of some mesons and their properties
Authoritative information on particle properties is compiled by the Particle Data Group http://pdg.lbl.gov
hep-ph/0211411: The light scalar mesons within quark models
Naming scheme for hadrons (a pdf file)

Recent Findings

This is a list of known and predicted Mesons. Mesons are made of Quarks and as such are part of the Subatomic particle family called the Hadrons This is a list of the different types of particles known and hypothesized In Physics, the quark model is a classification scheme for Hadrons in terms of their valence quarks, i

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