: ''This list is of all known and predicted

scalar Scalar may refer to: *Scalar (mathematics), an element of a field, which is used to define a vector space, usually the field of real numbers *Scalar (physics), a physical quantity that can be described by a single element of a number field such a ...

pseudoscalar In linear algebra, a pseudoscalar is a quantity that behaves like a scalar, except that it changes sign under a parity inversion while a true scalar does not. A pseudoscalar, when multiplied by an ordinary vector, becomes a '' pseudovector'' ...

and

vector Vector most often refers to: * Euclidean vector, a quantity with a magnitude and a direction * Disease vector, an agent that carries and transmits an infectious pathogen into another living organism Vector may also refer to: Mathematics a ...

meson In particle physics, a meson () 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, the ...

s. See

list of particles This is a list of known and hypothesized microscopic particles in particle physics, condensed matter physics and cosmology. Standard Model elementary particles Elementary particles are particles with no measurable internal structure; that is, ...

for a more detailed list of particles found in

particle physics Particle physics or high-energy physics is the study of Elementary particle, fundamental particles and fundamental interaction, forces that constitute matter and radiation. The field also studies combinations of elementary particles up to the s ...

.'' This article contains a list of mesons, unstable

subatomic particle In physics, a subatomic particle is a particle smaller than an atom. According to the Standard Model of particle physics, a subatomic particle can be either a composite particle, which is composed of other particles (for example, a baryon, lik ...

s composed of one

quark A quark () is a type of elementary particle and a fundamental constituent of matter. Quarks combine to form composite particles called hadrons, the most stable of which are protons and neutrons, the components of atomic nucleus, atomic nuclei ...

and one

antiquark A quark () is a type of elementary particle and a fundamental constituent of matter. Quarks combine to form composite particles called hadrons, the most stable of which are protons and neutrons, the components of atomic nuclei. All commonly ...

. They are part of the

hadron In particle physics, a hadron is a composite subatomic particle made of two or more quarks held together by the strong nuclear force. Pronounced , the name is derived . They are analogous to molecules, which are held together by the electri ...

particle family—particles made of quarks. The other members of the hadron family are the

baryon In particle physics, a baryon is a type of composite particle, composite subatomic particle that contains an odd number of valence quarks, conventionally three. proton, Protons and neutron, neutrons are examples of baryons; because baryons are ...

s—subatomic particles composed of three quarks. The main difference between

s and baryons is that mesons have integer

spin Spin or spinning most often refers to: * Spin (physics) or particle spin, a fundamental property of elementary particles * Spin quantum number, a number which defines the value of a particle's spin * Spinning (textiles), the creation of yarn or thr ...

(thus are

boson In particle physics, a boson ( ) is a subatomic particle whose spin quantum number has an integer value (0, 1, 2, ...). Bosons form one of the two fundamental classes of subatomic particle, the other being fermions, which have half odd-intege ...

s) while baryons are

fermion In particle physics, a fermion is a subatomic particle that follows Fermi–Dirac statistics. Fermions have a half-integer spin (spin 1/2, spin , Spin (physics)#Higher spins, spin , etc.) and obey the Pauli exclusion principle. These particles i ...

s (half-integer spin). Because mesons are bosons, the

Pauli exclusion principle In quantum mechanics, the Pauli exclusion principle (German: Pauli-Ausschlussprinzip) states that two or more identical particles with half-integer spins (i.e. fermions) cannot simultaneously occupy the same quantum state within a system that o ...

does not apply to them. Because of this, they can act as force mediating particles on short distances, and thus play a part in processes such as the nuclear interaction. Since mesons are composed of quarks, they participate in both the

weak Weak may refer to: Songs * Weak (AJR song), "Weak" (AJR song), 2016 * Weak (Melanie C song), "Weak" (Melanie C song), 2011 * Weak (SWV song), "Weak" (SWV song), 1993 * Weak (Skunk Anansie song), "Weak" (Skunk Anansie song), 1995 * "Weak", a son ...

and

strong interaction In nuclear physics and particle physics, the strong interaction, also called the strong force or strong nuclear force, is one of the four known fundamental interaction, fundamental interactions. It confines Quark, quarks into proton, protons, n ...

s. Mesons with net

electric charge Electric charge (symbol ''q'', sometimes ''Q'') is a physical property of matter that causes it to experience a force when placed in an electromagnetic field. Electric charge can be ''positive'' or ''negative''. Like charges repel each other and ...

also participate in the

electromagnetic interaction In physics, electromagnetism is an interaction that occurs between particles with electric charge via electromagnetic fields. The electromagnetic force is one of the four fundamental forces of nature. It is the dominant force in the interacti ...

. They are classified according to their quark content,

total angular momentum In quantum mechanics, the total angular momentum quantum number parametrises the total angular momentum of a given particle, by combining its orbital angular momentum and its intrinsic angular momentum (i.e., its spin). If s is the particle's ...

, parity, and various other properties such as

C-parity In physics, the C parity or charge parity is a multiplicative quantum number of some particles that describes their behavior under the symmetry operation of charge conjugation. Charge conjugation changes the sign of all quantum charges (that is, ...

and

G-parity In particle physics, G-parity is a multiplicative quantum number that results from the generalization of C-parity to multiplets of particles. ''C''-parity applies only to neutral systems; in the pion triplet, only π0 has ''C''-parity. On the ot ...

. While no meson is stable, those of lower

mass Mass is an Intrinsic and extrinsic properties, intrinsic property of a physical body, body. It was traditionally believed to be related to the physical quantity, quantity of matter in a body, until the discovery of the atom and particle physi ...

are nonetheless more stable than the most massive mesons, and are easier to observe and study in

particle accelerator A particle accelerator is a machine that uses electromagnetic fields to propel electric charge, charged particles to very high speeds and energies to contain them in well-defined particle beam, beams. Small accelerators are used for fundamental ...

s or in

cosmic ray Cosmic rays or astroparticles are high-energy particles or clusters of particles (primarily represented by protons or atomic nuclei) that move through space at nearly the speed of light. They originate from the Sun, from outside of the ...

experiments. They are also typically less massive than baryons, meaning that they are more easily produced in experiments, and will exhibit higher-energy phenomena sooner than baryons would. For example, the charm quark was first seen in the

J/Psi meson The (J/psi) meson is a subatomic particle, a flavor-neutral meson consisting of a charm quark and a charm antiquark. Mesons formed by a bound state of a charm quark and a charm anti-quark are generally known as " charmonium" or psions. The ...

() in 1974, and the bottom quark in the

upsilon meson The Upsilon meson () is a quarkonium state (i.e. flavourless meson) formed from a bottom quark and its antiparticle. It was discovered by the E288 experiment team, headed by Leon Lederman, at Fermilab in 1977, and was the first particle containi ...

() in 1977. The top quark (the last and heaviest quark to be discovered to date) was first observed at

Fermilab Fermi National Accelerator Laboratory (Fermilab), located in Batavia, Illinois, near Chicago, is a United States Department of Energy United States Department of Energy National Labs, national laboratory specializing in high-energy particle phys ...

in 1995. Each meson has a corresponding

antiparticle In particle physics, every type of particle of "ordinary" matter (as opposed to antimatter) is associated with an antiparticle with the same mass but with opposite physical charges (such as electric charge). For example, the antiparticle of the ...

(antimeson) where quarks are replaced by their corresponding antiquarks and vice versa. For example, a positive

pion In particle physics, a pion (, ) or pi meson, denoted with the Greek alphabet, Greek letter pi (letter), pi (), is any of three subatomic particles: , , and . Each pion consists of a quark and an antiquark and is therefore a meson. Pions are the ...

() is made of one up quark and one down antiquark; and its corresponding antiparticle, the negative pion (), is made of one up antiquark and one down quark. Although

tetraquark In particle physics, a tetraquark is an exotic meson composed of four valence quarks. A tetraquark state has long been suspected to be allowed by quantum chromodynamics, the modern theory of strong interactions. A tetraquark state is an example ...

s with two quarks and two antiquarks can be considered mesons they are not listed here. The symbols encountered in these lists are: P ( parity), C (

), G (

), u (

up quark The up quark or u quark (symbol: u) is the lightest of all quarks, a type of elementary particle, and a significant constituent of matter. It, along with the down quark, forms the neutrons (one up quark, two down quarks) and protons (two up quark ...

), d (

down quark The down quark (symbol: d) is a type of elementary particle, and a major constituent of matter. The down quark is the second-lightest of all quarks, and combines with other quarks to form composite particles called hadrons. Down quarks are most ...

), s (

strange quark The strange quark or s quark (from its symbol, s) is the third lightest of all quarks, a type of elementary particle. Strange quarks are found in subatomic particles called hadrons. Examples of hadrons containing strange quarks include kaons (), ...

), c (

charm quark The charm quark, charmed quark, or c quark is an elementary particle found in composite subatomic particles called hadrons such as the J/psi meson and the charmed baryons created in particle accelerator collisions. Several bosons, including th ...

), b (

bottom quark The bottom quark, beauty quark, or b quark, is an elementary particle of the third generation. It is a heavy quark with a charge of − ''e''. All quarks are described in a similar way by electroweak interaction and quantum chromodynamic ...

), ''I'' (

isospin In nuclear physics and particle physics, isospin (''I'') is a quantum number related to the up- and down quark content of the particle. Isospin is also known as isobaric spin or isotopic spin. Isospin symmetry is a subset of the flavour symmetr ...

), ''J'' (

), ''Q'' (

charge Charge or charged may refer to: Arts, entertainment, and media Films * ''Charge, Zero Emissions/Maximum Speed'', a 2011 documentary Music * ''Charge'' (David Ford album) * ''Charge'' (Machel Montano album) * '' Charge!!'', an album by The Aqu ...

), ''B'' (

baryon number In particle physics, the baryon number (B) is an additive quantum number of a system. It is defined as B = \frac(n_\text - n_), where is the number of quarks, and is the number of antiquarks. Baryons (three quarks) have B = +1, mesons (one q ...

), ''S'' (

strangeness In particle physics, strangeness (symbol ''S'') is a property of particles, expressed as a quantum number, for describing decay of particles in strong and electromagnetic interactions that occur in a short period of time. The strangeness of a ...

), ''C'' (

charm Charm or Charms may refer to: Arts and entertainment * The Charms, an American garage rock band * Otis Williams and the Charms, an American doo-wop group * The Charm (Bubba Sparxxx album), ''The Charm'' (Bubba Sparxxx album), 2006 * Charm (Danny! ...

), and ''B''′ (

bottomness In physics, bottomness (symbol ''B′''; using a prime as plain ''B'' is used already for baryon number) or beauty is a flavour quantum number reflecting the difference between the number of bottom antiquarks (''n'') and the number of bottom ...

), as well as a wide array of subatomic particles (hover mouse for name).

Summary table

Because this table was initially derived from published results and many of those results were preliminary, as many as 64 of the mesons in the following table may not exist or have the wrong mass or quantum numbers. Mesons named with the letter "f" are ''scalar mesons'' (as opposed to a pseudo-scalar meson), and mesons named with the letter "a" are axial-vector mesons (as opposed to an ordinary vector meson) a.k.a. an

isoscalar In particle physics, isoscalar refers to the scalar transformation of a particle or field under the SU(2) group of isospin. Isoscalars are a singlet state, with total isospin 0 and the third component of isospin 0, much like a singlet state in a 2-p ...

vector meson, while the letters "b" and "h" refer to axial-vector mesons with positive parity, negative C-parity, and quantum numbers I^G of 1⁺ and 0⁻ respectively. The, "f", "a", "b" and "h" mesons are not listed in the tables below and their internal structure and quark content is a matter of ongoing investigation. The particle described in the table above as f₀(500) has historically been known by two other names: f₀(600) and σ (sigma). A complete set of meson naming conventions is set forth in a 2017 review article for the Particle Data Group which also contains a table mapping pre-2016 common names to the new Particle Data Group standard naming conventions for XYZ mesons.

Meson properties

The following lists details for all known and predicted pseudoscalar ( ^P = 0⁻) and vector ( ^P = 1⁻) mesons. The properties and quark content of the particles are tabulated below; for the corresponding antiparticles, simply change quarks into antiquarks (and vice versa) and flip the sign of ''Q'', ''B'', ''S'', ''C'', and ''B''′. Particles with ^† next to their names have been predicted by the

standard model The Standard Model of particle physics is the Scientific theory, theory describing three of the four known fundamental forces (electromagnetism, electromagnetic, weak interaction, weak and strong interactions – excluding gravity) in the unive ...

but not yet observed. Values in have not been firmly established by experiments, but are predicted by the

quark model In particle physics, the quark model is a classification scheme for hadrons in terms of their valence quarks—the quarks and antiquarks that give rise to the quantum numbers of the hadrons. The quark model underlies "flavor SU(3)", or the Eig ...

and are consistent with the measurements.

Pseudoscalar mesons

\, , , 1⁻ , 0⁻⁺ , 0 , 0 , 0 , , , - , style="text-align:left", Eta mesonK.A. Olive ''et al''. (2014)
Particle listings –
/ref> , , Self , }\, , , 0⁺ , 0⁻⁺ , 0 , 0 , 0 , , or

, - , style="text-align:left", Eta prime mesonK.A. Olive ''et al''. (2014)
Particle listings –
/ref> , (958) , Self , \, , , 0⁺ , 0⁻⁺ , 0 , 0 , 0 , ,

, - , style="text-align:left", Charmed eta mesonK.A. Olive ''et al''. (2014)
Particle listings –
/ref> , (1S) , Self , , , 0⁺ , 0⁻⁺ , 0 , 0 , 0 ,
See decay modes
, - , style="text-align:left", Bottom eta mesonK.A. Olive ''et al''. (2014)
Particle listings –
/ref> , (1S) , Self , , , , ⁺ , 0 , 0 , 0 ,
See decay modes
, - , style="text-align:left", KaonK.A. Olive ''et al''. (2014)
Particle listings –
/ref> , , , , , , 0⁻ , 1 , 0 , 0 , ,

, - , style="text-align:left", KaonK.A. Olive ''et al''. (2014)
Particle listings –
/ref> , , , , , , 0⁻ , 1 , 0 , 0 , , , - , style="text-align:left", K-ShortK.A. Olive ''et al''. (2014)
Particle listings –
/ref> , , Self , }\, , , , 0⁻ , (*) , 0 , 0 , ,
, - , style="text-align:left", K-LongK.A. Olive ''et al''. (2014)
Particle listings –
/ref> , , Self , }\, , , , 0⁻ , (*) , 0 , 0 , ,

, - , style="text-align:left", D mesonK.A. Olive ''et al''. (2014)
Particle listings –
/ref> , , , , , , 0⁻ , 0 , +1 , 0 ,
See decay modes
, - , style="text-align:left", D mesonK.A. Olive ''et al''. (2014)
Particle listings –
/ref> , , , , , , 0⁻ , 0 , +1 , 0 ,
See decay modes
, - , style="text-align:left" , strange D mesonK.A. Olive ''et al''. (2014)
Particle listings –
/ref> , , , , , 0 , 0 , +1 , +1 , 0 ,
See decay modes
, - , style="text-align:left" , B mesonK.A. Olive ''et al''. (2014)
Particle listings –
/ref> , , , , , , , 0 , 0 , +1 ,
See decay modes
, - , style="text-align:left" , B mesonK.A. Olive ''et al''. (2014)
Particle listings –
/ref> , , , , , , , 0 , 0 , +1 ,
See decay modes
, - , style="text-align:left" , Strange B mesonK.A. Olive ''et al''. (2014)
Particle listings –
/ref> , , , , , , , −1 , 0 , +1 ,
See decay modes
, - , style="text-align:left" , Charmed B mesonK.A. Olive ''et al''. (2014)
Particle listings –
/ref> , , , , , , , 0 , +1 , +1 ,
See decay modes
^{/sup> Makeup inexact due to non-zero quark masses.

^{/sup> PDG reports the resonance width

In physics and engineering, the quality factor or factor is a Dimensionless quantity, dimensionless parameter that describes how underdamped an oscillator or resonator is. It is defined as the ratio of the initial energy stored in the resonato ...
(Γ). Here the conversion ''τ'' = is given instead.

^{/sup> Strong
Strong may refer to:

Education
* The Strong, an educational institution in Rochester, New York, United States
* Strong Hall (Lawrence, Kansas), an administrative hall of the University of Kansas
* Strong School, New Haven, Connecticut, United ...
eigenstate

In quantum physics, a quantum state is a mathematical entity that embodies the knowledge of a quantum system. Quantum mechanics specifies the construction, evolution, and measurement of a quantum state. The result is a prediction for the system re ...
. No definite lifetime (see kaon notes below)

^{/sup> The mass of the and are given as that of the . However, it is known that a difference between the masses of the and on the order of exists.

^{/sup> Weak

Weak may refer to:
Songs
* Weak (AJR song), "Weak" (AJR song), 2016
* Weak (Melanie C song), "Weak" (Melanie C song), 2011
* Weak (SWV song), "Weak" (SWV song), 1993
* Weak (Skunk Anansie song), "Weak" (Skunk Anansie song), 1995
* "Weak", a son ...
eigenstate

In quantum physics, a quantum state is a mathematical entity that embodies the knowledge of a quantum system. Quantum mechanics specifies the construction, evolution, and measurement of a quantum state. The result is a prediction for the system re ...
. Makeup is missing small CP–violating term (see notes on neutral kaons below).

Vector mesons

,
, 1⁺
, 1⁻⁻
, 0
, 0
, 0
,
,
, -
, style="text-align:left" , Omega mesonK.A. Olive ''et al''. (2014)
Particle listings – (782)
/ref>
, (782)
, Self
, }
,
, 0⁻
, 1⁻⁻
, 0
, 0
, 0
,
,

, -
, style="text-align:left" , Phi mesonK.A. Olive ''et al''. (2014)
Particle listings –
/ref>
, (1020)
, Self
,
,
, 0⁻
, 1⁻⁻
, 0
, 0
, 0
,
,

, -
, style="text-align:left" , J/PsiK.A. Olive ''et al''. (2014)
Particle listings – J/Ψ
/ref>
,
, Self
,
,
, 0⁻
, 1⁻⁻
, 0
, 0
, 0
,

See (1S) decay modes
, -
, style="text-align:left" , Upsilon mesonK.A. Olive ''et al''. (2014)
Particle listings – (1S)
/ref>
, (1S)
, Self
,
,
, 0⁻
, 1⁻⁻
, 0
, 0
, 0
,

See (1S) decay modes
, -
, style="text-align:left" , KaonK.A. Olive ''et al''. (2014)
Particle listings – (892)
/ref>
,
,
,
,
,
, 1⁻
, 1
, 0
, 0
,

See (892) decay modes
, -
, style="text-align:left" , Kaon
,
,
,
,
,
, 1⁻
, 1
, 0
, 0
,

See (892) decay modes
, -
, style="text-align:left" , D mesonK.A. Olive ''et al''. (2014)
Particle listings – (2010)
/ref>
, (2010)
, (2010)
,
,
,
,
, 0
, +1
, 0
,
,

, -
, style="text-align:left" , D mesonK.A. Olive ''et al''. (2014)
Particle listings – (2007)
/ref>
, (2007)
, (2007)
,
,
,
,
, 0
, +1
, 0
,
,

, -
, style="text-align:left" , Strange D mesonK.A. Olive ''et al''. (2014)
Particle listings –
/ref>
,
,
,
,
,
,
, +1
, +1
, 0
,
,

, -
, style="text-align:left" , B mesonK.A. Olive ''et al''. (2014)
Particle listings –
/ref>
,
,
,
,
,
,
, 0
, 0
, +1
, Unknown
,
, -
, style="text-align:left" , B meson
,
,
,
,
,
,
, 0
, 0
, +1
, Unknown
,
, -
, style="text-align:left" , Strange B mesonK.A. Olive ''et al''. (2014)
Particle listings –
/ref>
,
,
,
,
,
,
, −1
, 0
, +1
, Unknown
,
, -
, style="text-align:left" , Charmed B meson^†
,
,
,
, Unknown
,
,
, 0
, +1
, +1
, Unknown
, Unknown

^{/sup> PDG reports the resonance width

In physics and engineering, the quality factor or factor is a Dimensionless quantity, dimensionless parameter that describes how underdamped an oscillator or resonator is. It is defined as the ratio of the initial energy stored in the resonato ...
(Γ). Here the conversion ''τ'' = is given instead.

^{/sup> The exact value depends on the method used. See the given reference for detail.

Notes on neutral kaons

There are two complications with neutral

Neutral or neutrality may refer to:

Mathematics and natural science Biology
* Neutral organisms, in ecology, those that obey the unified neutral theory of biodiversity
Chemistry and physics
* Neutralization (chemistry), a chemical reaction in ...
kaon

In particle physics, a kaon, also called a K meson and denoted , is any of a group of four mesons distinguished by a quantum number called strangeness. In the quark model they are understood to be bound states of a strange quark (or antiquark ...
s:
* Due to neutral kaon mixing, the and are not eigenstate

In quantum physics, a quantum state is a mathematical entity that embodies the knowledge of a quantum system. Quantum mechanics specifies the construction, evolution, and measurement of a quantum state. The result is a prediction for the system re ...
s of strangeness

In particle physics, strangeness (symbol ''S'') is a property of particles, expressed as a quantum number, for describing decay of particles in strong and electromagnetic interactions that occur in a short period of time. The strangeness of a ...
. However, they ''are'' eigenstates of the weak force

In nuclear physics and particle physics, the weak interaction, weak force or the weak nuclear force, is one of the four known fundamental interactions, with the others being electromagnetism, the strong interaction, and gravitation. It is th ...
, which determines how they decay
Decay may refer to:

Science and technology
* Bit decay, in computing
* Decay time (fall time), in electronics
* Distance decay, in geography
* Software decay, in computing
Biology
* Decomposition of organic matter
* Mitochondrial decay, in g ...
, so these are the particles with definite lifetime.
* The linear combination

In mathematics, a linear combination or superposition is an Expression (mathematics), expression constructed from a Set (mathematics), set of terms by multiplying each term by a constant and adding the results (e.g. a linear combination of ''x'' a ...
s given in the table for the and are not exactly correct, since there is a small correction due to CP violation

In particle physics, CP violation is a violation of CP-symmetry (or charge conjugation parity symmetry): the combination of C-symmetry (charge conjugation symmetry) and P-symmetry ( parity symmetry). CP-symmetry states that the laws of physics s ...
. See CP violation in kaons.

Note that these issues also exist in principle for other neutral flavored mesons; however, the weak eigenstates are considered separate particles only for kaons because of their dramatically different lifetimes.J.W. Cronin (1980)

See also

* List of baryons

Baryons are composite particles made of three quarks, as opposed to mesons, which are composite particles made of an equal number of quarks and antiquarks. Baryons and mesons are both hadrons, which are particles composed solely of quarks or bot ...

* List of particles
This is a list of known and hypothesized microscopic particles in particle physics, condensed matter physics and cosmology.
Standard Model elementary particles

Elementary particles are particles with no measurable internal structure; that is, ...

* Timeline of particle discoveries

This is a timeline of subatomic particle discoveries, including all particles thus far discovered which appear to be elementary (that is, indivisible) given the best available evidence. It also includes the discovery of composite particles and a ...

References

Bibliography

*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*
*

External links

* Particle Data Group

The Particle Data Group (PDG) is an international collaboration of particle physicists that compiles and reanalyzes published results related to the properties of particles and fundamental interactions. It also publishes reviews of theoretical ...
: ''The Review of Particle Physics''
pdgLive – Meson Summary Table

Mesons made thinkable
an interactive visualisation allowing physical properties to be compared

{{particles

*
Mesons

In particle physics, a meson () 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, the ...

it:Lista dei mesoni}}}}}}}