List of mesons

The decay of a kaon (K+) into three pions (2 π+, 1 π−) is a process that involves both weak and strong interactions.

Weak interactions: The strange antiquark (s) of the kaon transmutes into an up antiquark (u) by the emission of a W+ boson; the W+ boson subsequently decays into a down antiquark (d) and an up quark (u).

Strong interactions: An up quark (u) emits a gluon (g) which decays into a down quark (d) and a down antiquark (d).

This list is of all known and predicted scalar, pseudoscalar and vector mesons. See list of particles for a more detailed list of particles found in particle physics.

Mesons are unstable subatomic particles composed of one quark and one antiquark. They are part of the hadron particle family – particles made of quarks. The other members of the hadron family are the baryons – subatomic particles composed of three quarks. The main difference between mesons and baryons is that mesons have integer spin (thus are bosons) while baryons are fermions (half-integer spin). Because mesons are bosons, the Pauli exclusion principle 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 and strong interactions. Mesons with net electric charge also participate in the electromagnetic interaction. They are classified according to their quark content, total angular momentum, parity, and various other properties such as C-parity and G-parity. While no meson is stable, those of lower mass are nonetheless more stable than the most massive mesons, and are easier to observe and study in particle accelerators or in cosmic ray 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 (J/ψ) in 1974, and the bottom quark in the upsilon meson (ϒ) in 1977.

Each meson has a corresponding antiparticle (antimeson) where 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. Some experiments show the evidence of tetraquarks – "exotic" mesons made of two quarks and two antiquarks, but the particle physics community as a whole does not view their existence as likely, although still possible.

The symbols encountered in these lists are: I (isospin), J (total angular momentum), P (parity), C (C-parity), G (G-parity), u (up quark), d (down quark), s (strange quark), c (charm quark), b (bottom quark), Q (charge), B (baryon number), S (strangeness), C (charm), and B′ (bottomness), as well as a wide array of subatomic particles (hover 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.

Meson summary table

Light unflavoured (S=C=B=0)				Strange (S=±1, C=B=0)		Charmed, strange (C=S=±1)		cc
	IG(JPC)		IG(JPC)		IG(JP)		IG(JP)		IG(JPC)
π±	1−(0−)	φ(1680)	0−(1−−)	K±	1/2(0−)	D± s	0(0−)	η c(1S)	0+(0−+)
π0	1−(0−+)	ρ 3(1690)	1+(3−−)	K0	1/2(0−)	D*± s	0(??)	J/ψ(1S)	0−(1−−)
η	0+(0−+)	ρ(1700)	1+(1−−)	K0 S	1/2(0−)	D* s0(2317)±	0(0+)	χ c0(1P)	0+(0++)
f 0(500)	0+(0++)	a 2(1700)	1−(2++)	K0 L	1/2(0−)	D s1(2460)±	0(1+)	χ c1(1P)	0+(1++)
ρ(770)	1+(1−−)	f0(1710)	0+(0++)	K* 0(800)	1/2(0+)	D s1(2536)±	0(1+)	h c(1P)	??(1+−)
ω(782)	0−(1−−)	η(1760)	0+(0−+)	K*(892)	1/2(1−)	D s2(2573)	0(??)	χ c2(1P)	0+(2++)
η′ (958)	0+(0−+)	π(1800)	1−(0−+)	K 1(1270)	1/2(1+)	D* s1(2700)±	0(1−)	η c(2S)	0+(0−+)
f 0(980)	0+(0++)	f 2(1810)	0+(2++)	K 1(1400)	1/2(1+)	D* sJ(2860)±	0(??)	ψ(2S)	0−(1−−)
a 0(980)	1−(0++)	X(1835)	??(?−+)	K*(1410)	1/2(1−)	D sJ(3040)±	0(??)	ψ(3770)	0−(1−−)
φ(1020)	0−(1−−)	X(1840)	??(???)	K* 0(1430)	1/2(0+)	Bottom (B=±1)		X(3823)	??(??−)
h 1(1170)	0−(1+−)	φ 3(1850)	0−(3−−)	K* 2(1430)	1/2(2+)			X(3872)	0+(1++)
b 1(1235)	1+(1+−)	η 2(1870)	0+(2−+)	K(1460)	1/2(0−)	B±	1/2(0−)	X(3900)±	?(1+)
a 1(1260)	1−(1++)	π 2(1880)	1−(2−+)	K 2(1580)	1/2(2−)	B0	1/2(0−)	X(3900)0	?(??)
f 2(1270)	0+(2++)	ρ(1900)	1+(1−−)	K(1630)	1/2(??)	B±/B0 Admixture		χ c0(2P)	0+(0++)
f 1(1285)	0+(1++)	f 2(1910)	0+(2++)	K 1(1650)	1/2(1+)	B±/B0/B0 s/b-baryon Admixture		χ c2(2P)	0+(2++)
η(1295)	0+(0−+)	f 2(1950)	0+(2++)	K*(1680)	1/2(1−)			X(3940)	??(???)
π(1300)	1−(0−+)	ρ 3(1990)	1+(3−−)	K 2(1770)	1/2(2−)	Vcb and Vub CKM Matrix Admixture		X(4020)±	?(??)
a 2(1320)	1−(2++)	f 2(2010)	0+(2++)	K* 3(1780)	1/2(3−)			ψ(4040)	0−(1−−)
f 0(1370)	0+(0++)	f 0(2020)	0+(0++)	K 2(1820)	1/2(2−)	B*	1/2(1−)	X(4050)±	?(??)
h 1(1380)	?−(1+−)	a 4(2040)	1−(4++)	K(1830)	1/2(0−)	B* J(5732)	?(??)	X(4140)	0+(??+)
π 1(1400)	1−(1−+)	f 4(2050)	0+(4++)	K* 0(1950)	1/2(0+)	B 1(5721)0	1/2(1+)	ψ(4160)	0−(1−−)
η(1405)	0+(0−+)	π 2(2100)	1−(2−+)	K* 2(1980)	1/2(2+)	B* 1(5721)0	1/2(2+)	X(4160)	??(???)
f 1(1420)	0+(1++)	f 0(2100)	0+(0++)	K* 0(2045)	1/2(4+)	Bottom, strange (B=±1, S=∓1)		X(4250)±	?(??)
ω(1420)	0−(1−−)	f 2(2150)	0+(2++)	K 2(2250)	1/2(2−)			X(4260)	??(1−−)
f 2(1430)	0+(2++)	ρ(2150)	1+(1−−)	K 3(2320)	1/2(3+)	B0 s	0(0−)	X(4350)	0+(??+)
a 0(1450)	1−(0++)	φ(2170)	0−(1−−)	K* 5(2380)	1/2(5−)	B* s	0(1−)	X(4360)	??(1−−)
ρ(1450)	1+(1−−)	f 0(2200)	0+(0++)	k 4(2500)	1/2(4−)	B s1(5830)0	0(1+)	ψ(4415)	0−(1−−)
η(1475)	0+(0−+)	fJ(2200)	0+(2++ or 4++)	K(3100)	??(???)	B* s2(5840)0	0(2+)	X(4430)±	?(1+)
f 0(1500)	0+(0++)			Charmed (C=±1)		B* sJ(5850)	?(??)	X(4660)	??(1−−)
f 1(1510)	0+(1++)	η(2225)	0+(0−+)			Bottom, charmed (B=C=±1)		bb
f′ 1(1525)	0+(2++)	ρ 3(2250)	1+(3−−)	D±	1/2(0−)			η b(1S)	0+(0−+)
f 2(1565)	0+(2++)	f2(2300)	0+(2++)	D0	1/2(0−)	B± c	0(0−)	Υ(1S)	0−(1−−)
ρ(1570)	1+(1−−)	f 4(2300)	0+(4++)	D*(2007)0	1/2(1−)			χ b0(1P)	0+(0++)
h 1(1595)	0−(1+−)	f 0(2330)	0+(0++)	D*(2010)±	1/2(1−)			χ b1(1P)	0+(1++)
π 1(1600)	1−(1−+)	f 2(2340)	0+(2++)	D* 0(2400)0	1/2(0+)			χ b0(2P)	0+(0++)
a 1(1640)	1−(1++)	ρ 5(2350)	1+(5−−)	D* 0(2400)±	1/2(0+)			h b(1P)	??(1+−)
f 2(1640)	0+(2++)	a 6(2450)	1−(6++)	D 1(2420)0	1/2(1+)			χ b2(1P)	0+(2++)
η 2(1645)	0+(2−+)	f 6(2510)	0+(6++)	D 1(2420)±	1/2(??)			η b(2S)	0+(0−+)
ω(1650)	0−(1−−)	Other Light		D 1(2430)0	1/2(1+)			Υ(2S)	0−(1−−)
ω 3(1670)	0−(3−−)	Further States		D* 2(2460)0	1/2(2+)			Υ(1D)	0−(2−−)
π 2(1670)	1−(2−+)			D* 2(2460)±	1/2(2+)			χ b0(2P)	0+(0++)
				D(2550)0	1/2(0−)			χ b1(2P)	0+(1++)
				D(2600)	1/2(??)			h b(2P)	??(1+−)
				D*(2640)±	1/2(??)			χ b2(2P)	0+(2++)
				D(2750)	1/2(??)			Υ(3S)	0−(1−−)
								χ b(3P)	??(??+)
								Υ(4S)	0−(1−−)
								X(10610)±	1+(1+)
								X(10610)0	1+(1+)
								X(10650)±	?+(1+)
								Υ(10860)	0−(1−−)
								Υ(11020)	0−(1−−)

Meson properties

The following lists detail all known and predicted pseudoscalar (J^P = 0⁻) and vector (J^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 but not yet observed. Values in red have not been firmly established by experiments, but are predicted by the quark model and are consistent with the measurements.

Pseudoscalar mesons

Pseudoscalar mesons

Particle name	Particle symbol	Antiparticle symbol	Quark content	Rest mass (MeV/c2)	IG	JPC	S	C	B'	Mean lifetime (s)	Commonly decays to (>5% of decays)
Pion	π+	π−	ud	139.57018±0.00035	1−	0−	0	0	0	(2.6033±0.0005)×10−8	μ+ + ν μ
Pion	π0	Self	$\mathrm{\tfrac{u\bar{u} - d\bar{d}}{\sqrt{2}}}\,$	134.9766±0.0006	1−	0−+	0	0	0	(8.52±0.18)×10−17	γ + γ
Eta meson	η	Self	$\mathrm{\tfrac{u\bar{u} + d\bar{d} - 2s\bar{s}}{\sqrt{6}}}\,$	547.862±0.018	0+	0−+	0	0	0	(5.02±0.19)×10−19	γ + γ or π0 + π0 + π0 or π+ + π0 + π−
Eta prime meson	η′(958)	Self	$\mathrm{\tfrac{u\bar{u} + d\bar{d} + s\bar{s}}{\sqrt{3}}}\,$	957.78±0.06	0+	0−+	0	0	0	(3.32±0.15)×10−21	π+ + π− + η or (ρ0 + γ) / (π+ + π− + γ) or π0 + π0 + η
Charmed eta meson	η c(1S)	Self	cc	2983.6±0.7	0+	0−+	0	0	0	(2.04±0.05)×10−23	See η c decay modes
Bottom eta meson	η b(1S)	Self	bb	9398.0±3.2	0+	0−+	0	0	0	Unknown	See η b decay modes
Kaon	K+	K−	us	493.677±0.016	​1⁄2	0−	1	0	0	(1.2380±0.0021)×10−8	μ+ + ν μ or π+ + π0 or π0 + e+ + ν e or π+ + π+ + π−
Kaon	K0	K0	ds	497.614±0.024	​1⁄2	0−	1	0	0
K-Short	K0 S	Self	$\mathrm{\tfrac{d\bar{s} - s\bar{d}}{\sqrt{2}}}\,$	497.614±0.024	​1⁄2	0−	(*)	0	0	(8.954±0.004)×10−11	π+ + π− or π0 + π0
K-Long	K0 L	Self	$\mathrm{\tfrac{d\bar{s} + s\bar{d}}{\sqrt{2}}}\,$	497.614±0.024	​1⁄2	0−	(*)	0	0	(5.116±0.021)×10−8	π± + e∓ + ν e or π± + μ∓ + ν μ or π0 + π0 + π0 or π+ + π0 + π−
D meson	D+	D−	cd	1869.61±0.10	​1⁄2	0−	0	+1	0	(1.040±0.007)×10−12	See D+ decay modes
D meson	D0	D0	cu	1864.84±0.07	​1⁄2	0−	0	+1	0	(4.101±0.015)×10−13	See D0 decay modes
strange D meson	D+ s	D− s	cs	1968.30±0.11	0	0−	+1	+1	0	(5.00±0.07)×10−13	See D+ s decay modes
B meson	B+	B−	ub	5279.26±0.17	​1⁄2	0−	0	0	+1	(1.638±0.004)×10−12	See B+ decay modes
B meson	B0	B0	db	5279.58±0.17	​1⁄2	0−	0	0	+1	(1.519±0.009)×10−12	See B0 decay modes
Strange B meson	B0 s	B0 s	sb	5366.77±0.24	0	0−	−1	0	+1	(1.512±0.007)×10−12	See B0 s decay modes
Charmed B meson	B+ c	B− c	cb	6275.6±1.1	0	0−	0	+1	+1	(4.52±0.33)×10−13	See B+ c decay modes

^[a] ^ Makeup inexact due to non-zero quark masses.
^[b] ^ PDG reports the resonance width (Γ). Here the conversion τ = ​^ħ⁄_Γ is given instead.
^[c] ^ Strong eigenstate. No definite lifetime (see kaon notes below)
^[d] ^ The mass of the K0
L and K0
S are given as that of the K0. However, it is known that a difference between the masses of the K0
L and K0
S on the order of 2.2×10⁻¹¹ MeV/c² exists.
^[e] ^ Weak eigenstate. Makeup is missing small CP–violating term (see notes on neutral kaons below).

Vector mesons

Vector mesons

Particle name	Particle symbol	Antiparticle symbol	Quark content	Rest mass (MeV/c2)	IG	JPC	S	C	B'	Mean lifetime (s)	Commonly decays to (>5% of decays)
Charged rho meson	ρ+(770)	ρ−(770)	ud	775.11±0.34	1+	1−	0	0	0	(4.41±0.02)×10−24	π± + π0
Neutral rho meson	ρ0(770)	Self	$\mathrm{\tfrac{u\bar{u}-d\bar{d}}{\sqrt 2}}\,$	775.26±0.25	1+	1−−	0	0	0	(4.45±0.03)×10−24	π+ + π−
Omega meson	ω(782)	Self	$\mathrm{\tfrac{u\bar{u} + d\bar{d}}{\sqrt{2}}}\,$	782.65±0.12	0−	1−−	0	0	0	(7.75±0.07)×10−23	π+ + π0 + π− or π0 + γ
Phi meson	ϕ(1020)	Self	ss	1019.461±0.019	0−	1−−	0	0	0	(1.54±0.01)×10−22	K+ + K− or K0 S + K0 L or (ρ + π) / (π+ + π0 + π−)
J/Psi	J/ψ	Self	cc	3096.916±0.011	0−	1−−	0	0	0	(7.09±0.21)×10−21	See J/ψ(1S) decay modes
Upsilon meson	ϒ(1S)	Self	bb	9460.30±0.26	0−	1−−	0	0	0	(1.22±0.03)×10−20	See ϒ(1S) decay modes
Kaon	K∗+	K∗−	us	891.66±0.026	​1⁄2	1−	1	0	0	(3.26±0.06)×10−23	See K∗(892) decay modes
Kaon	K∗0	K∗0	ds	895.81±0.19	​1⁄2	1−	1	0	0	(1.39±0.02)×10−23	See K∗(892) decay modes
D meson	D∗+(2010)	D∗−(2010)	cd	2010.26±0.07	​1⁄2	1−	0	+1	0	(7.89±0.17)×10−21	D0 + π+ or D+ + π0
D meson	D∗0(2007)	D∗0(2007)	cu	2006.96±0.10	​1⁄2	1−	0	+1	0	>3.1×10−22	D0 + π0 or D0 + γ
Strange D meson	D∗+ s	D∗− s	cs	2112.1±0.4	0	1−	+1	+1	0	>3.4×10−22	D∗+ + γ or D∗+ + π0
B meson	B∗+	B∗−	ub	5325.2±0.4	​1⁄2	1−	0	0	+1	Unknown	B+ + γ
B meson	B∗0	B∗0	db	5325.2±0.4	​1⁄2	1−	0	0	+1	Unknown	B0 + γ
Strange B meson	B∗0 s	B∗0 s	sb	5415.4+2.4 −2.1	0	1−	−1	0	+1	Unknown	B0 s+γ
Charmed B meson†	B∗+ c	B∗− c	cb	Unknown	0	1−	0	+1	+1	Unknown	Unknown

^[f] ^ PDG reports the resonance width (Γ). Here the conversion τ = ​^ħ⁄_Γ is given instead.
^[g] ^ The exact value depends on the method used. See the given reference for detail.

Notes on neutral kaons

There are two complications with neutral kaons:

• Due to neutral kaon mixing, the K0
  S and K0
  L are not eigenstates of strangeness. However, they are eigenstates of the weak force, which determines how they decay, so these are the particles with definite lifetime.
• The linear combinations given in the table for the K0
  S and K0
  L are not exactly correct, since there is a small correction due to CP violation. 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.

See also

• List of baryons
• List of particles
• Timeline of particle discoveries

External links

• Particle Data Group – The Review of Particle Physics (2008)
• Mesons made thinkable, an interactive visualisation allowing physical properties to be compared