- 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,[1][2] and the bottom quark in the upsilon meson (ϒ) in 1977.[3]
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 antiquark, but the particle physics community as a whole does not view their existence as likely, although still possible.[4]Contents
Summary table
MESON SUMMARY TABLE[5] LIGHT UNFLAVOURED
(S=C=B=0)STRANGE
(S=±1, C=B=0)CHARMED
(C=±1, B=0)BOTTOM
(B=±1)IG(JPC) IG(JPC) IG(JP) IG(JP) IG(JPC) π± 1−(0−) π2(1670) 1−(2−+) K± ½(0−) D± ½(0−) B± ½(0−) π0 1−(0−+) φ(1680) 0−(1−−) K0 ½(0−) D0 ½(0−) B0 ½(0−) η 0+(0−+) ρ3(1690) 1+(3−−) K0S ½(0−) D*(2007)0 ½(1−) B±/B0 Admixture f0(600) 0+(0++) ρ(1700) 1+(1−−) K0L ½(0−) D*(2010)± ½(1−) B±/B0/B0s/b-baryon
Admixtureρ(770) 1+(1−−) a2(1700) 1−(2++) K*0(800) ½(0+) D*0(2400)0 ½(0+) ω(782) 0−(1−−) f0(1710) 0+(0++) K*(892) ½(1−) D*0(2400)± ½(0+) B* ½(1−) η'(958) 0+(0−+) η(1760) 0+(0−+) K1(1270) ½(1+) D1(2420)0 ½(1+) B*J(5732) ?(??) f0(980) 0+(0++) π(1800) 1−(0−+) K1(1400) ½(1+) D1(2420)± ½(??) B1(5721)0 ½(1+) a0(980) 1−(0++) f2(1810) 0+(2++) K*(1410) ½(1−) D1(2430)0 ½(1+) B*2(5747)0 ½(2+) φ(1020) 0−(1−−) X(1835) ??(?−+) K*0(1430) ½(0+) D*2(2460)0 ½(2+) BOTTOM STRANGE h1(1170) 0−(1+−) φ3(1850) 0−(3−−) K*2(1430) ½(2+) D*2(2460)± ½(2+) B0s 0(0−) b1(1235) 1+(1+−) η2(1870) 0+(2−+) K(1460) ½(0−) D*(2640)± ½(??) B*s 0(1−) a1(1260) 1−(1++) π2(1880) 1−(2−+) K2(1580) ½(2−) CHARMED STRANGE Bs1(5830)0 ½(1+) f2(1270) 0+(2++) ρ(1900) 1+(1−−) K(1630) ½(??) D±s 0(0−) B*s2(5840)0 ½(2+) f1(1285) 0+(1++) f2(1910) 0+(2++) K1(1650) ½(1+) D*±s 0(??) B*sJ(5850) ?(??) η(1295) 0+(0−+) f2(1950) 0+(2++) K*(1680) ½(1−) D*s0(2317)± 0(0+) BOTTOM CHARMED π(1300) 1−(0−+) ρ3(1990) 1+(3−−) K2(1770) ½(2−) Ds1(2460)± 0(1+) B±c 0(0−) a2(1320) 1−(2++) f2(2010) 0+(2++) K*3(1780) ½(3−) Ds1(2536)± 0(1+) BOTTOM BOTTOM f0(1370) 0+(0++) f0(2020) 0+(0++) K2(1820) ½(2−) Ds2(2573) 0(??) ηb(1S) 0+(0−+) h1(1380) ?−(1+−) a4(2040) 1−(4++) K(1830) ½(0−) D*s1(2700)± 0(1−) Υ(1S) 0−(1−−) π1(1400) 1−(1−+) f4(2050) 0+(4++) K*0(1950) ½(0+) D*sJ(2860)± 0(??) χb0(1P) 0+(0++) η(1405) 0+(0−+) π2(2100) 1−(2−+) K*2(1980) ½(2+) DsJ(3040)± 0(??) χb1(1P) 0+(1++) f1(1420) 0+(1++) f0(2100) 0+(0++) K*4(2045) ½(4+) CHARMED CHARMED χb2(1P) 0+(2++) ω(1420) 0−(1−−) f2(2150) 0+(2++) K2(2250) ½(2−) ηc(1S) 0+(0−+) Υ(2S) 0−(1−−) f2(1430) 0+(2++) ρ(2150) 1+(1−−) K3(2320) ½(3+) J/ψ(1S) 0−(1−−) Υ(1D) 0−(2−−) a0(1450) 1−(0++) φ(2150) 0−(1−−) K*5(2380) ½(5−) χc0(1P) 0+(0++) χb0(2P) 0+(0++) ρ(1450) 1+(1−−) f0(2200) 0+(2++
or 4++)K4(2500) ½(4−) χc1(1P) 0+(1++) χb1(2P) 0+(1++) η(1450) 0+(0−+) K(3100) ??(???) hc(1P) ??(1+−) χb2(2P) 0+(2++) f0(1500) 0+(0++) η(2225) 0+(0−+) χc2(1P) 0+(2++) Υ(3S) 0−(1−−) f1(1510) 0+(1++) ρ3(2250) 1+(3−−) ηc(2S) 0+(0−+) Υ(4S) 0−(1−−) f'2(1525) 0+(2++) f2(2300) 0+(2++) ψ(2S) 0−(1−−) Υ(10860) 0−(1−−) f2(1565) 0+(2++) f4(2300) 0+(4++) ψ(3770) 0−(1−−) Υ(11020) 0−(1−−) ρ(1570) 1+(1−−) f0(2330) 0+(0++) X(3872) 0?(??+) h1(1595) 0−(1+−) f2(2340) 0+(2++) χc2(2P) 0+(2++) π1(1600) 1−(1−+) ρ5(2350) 1+(5−−) X(3940) ??(???) a1(1640) 1−(1++) a6(2450) 1−(6++) X(3945) 0+(??+) f2(1640) 0+(2++) f6(2510) 0+(6++) ψ(4040) 0−(1−−) η2(1645) 0+(2−+) X(4050)± ?(??) ω(1650) 0−(1−−) X(4140) 0+(??+) ω3(1670) 0−(3−−) ψ(4160) 0−(1−−) X(4160) ??(???) X(4250)± ?(??) X(4260) ??(1−−) X(4350) 0+(??+) X(4360) ??(1−−) ψ(4415) 0−(1−−) X(4430)± ?(??) X(4660) ??(1−−) 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 above table may not exist or have the wrong mass or quantum numbers.
List of mesons
These lists detail all known and predicted pseudoscalar (JP = 0−) and vector (JP = 1−) mesons.
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).
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
symbolAntiparticle
symbolQuark
contentRest mass (MeV/c2) IG JPC S C B' Mean lifetime (s) Commonly decays to
(>5% of decays)
Pion[6] π+ π− ud 139.57018±0.00035 1− 0− 0 0 0 2.6033±0.0005×10−8 μ+
+ ν
μPion[7] π0 Self [a]
134.9766±0.0006 1− 0−+ 0 0 0 8.4±0.5×10−17 γ + γ Eta meson[8] η Self [a]
547.853±0.024 0+ 0−+ 0 0 0 5.0±0.3×10−19[b] γ + γ or
π0
+ π0
+ π0
or
Eta prime meson[9] η′(958) Self [a]
957.78±0.06 0+ 0−+ 0 0 0 3.39±0.16×10−21[b] π+
+ π−
+ η or
Charmed eta meson[10] η
c(1S)Self cc 2,980.3±1.2 0+ 0−+ 0 0 0 2.30±0.17×10−23[b] See η
c decay modesBottom eta meson[11] η
b(1S)Self bb 9,390.9±2.8 0+ 0−+ 0 0 0 Unknown See η
b decay modesKaon[12] K+ K− us 493.677±0.016 1⁄2 0− 1 0 0 1.2380±0.0021×10−8 μ+
+ ν
μ or
Kaon[13] K0 K0 ds 497.614±0.024 1⁄2 0− 1 0 0 [c] [c] K-Short[14] K0
SSelf [e]
497.614±0.024[d] 1⁄2 0− (*) 0 0 8.953±0.005×10−11 π+
+ π−
or
K-Long[15] K0
LSelf [e]
497.614±0.024[d] 1⁄2 0− (*) 0 0 5.116±0.020×10−8 π±
+ e∓
+ ν
e or
π±
+ μ∓
+ ν
μ or
D meson[16] D+ D− cd 1,869.60±0.16 1⁄2 0− 0 +1 0 1.040±0.007×10−12 See D+
decay modesD meson[17] D0 D0 cu 1,864.83±0.14 1⁄2 0− 0 +1 0 4.101±0.015×10−13 See D0
decay modesstrange D meson[18] D+
sD−
scs 1,968.47±0.33 0 0− +1 +1 0 5.00±0.07×10−13 See D+
s decay modesB meson[19] B+ B− ub 5,279.15±0.31 1⁄2 0− 0 0 +1 1.638±0.011×10−12 See B+
decay modesB meson[20] B0 B0 db 5,279.50±0.30 1⁄2 0− 0 0 +1 1.530±0.009×10−12 See B0
decay modesStrange B meson[21] B0
sB0
ssb 5,366.3±0.6 0 0− −1 0 +1 1.472+0.024
−0.026×10−12See B0
s decay modesCharmed B meson[22] B+
cB−
ccb 6,277±6 0 0− 0 +1 +1 4.53±0.41×10−13 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.[15]
[e] ^ Weak eigenstate. Makeup is missing small CP–violating term (see notes on neutral kaons below).Vector mesons
Vector mesons Particle name Particle
symbolAntiparticle
symbolQuark
contentRest mass (MeV/c2) IG JPC S C B' Mean lifetime (s) Commonly decays to
(>5% of decays)
Charged rho meson[23] ρ+
(770)ρ−
(770)ud 775.11±0.34 1+ 1− 0 0 0 ~4.5×10−24[f][g] π±
+ π0Neutral rho meson[23] ρ0
(770)Self 775.49±0.34 1+ 1−− 0 0 0 ~4.5×10−24[f][g] π+
+ π−Omega meson[24] ω(782) Self 782.65±0.12 0− 1−− 0 0 0 7.75±0.07×10−23[f] π+
+ π0
+ π−
or
Phi meson[25] φ(1020) Self ss 1,019.445±0.020 0− 1−− 0 0 0 1.55±0.01×10−22[f] K+
+ K−
or
K0
S + K0
L or
(ρ + π) / (π+
+ π0
+ π−
)J/Psi[26] J/ψ Self cc 3,096.916±0.011 0− 1−− 0 0 0 7.09±0.21×10−21[f] See J/ψ(1S) decay modes Upsilon meson[27] ϒ(1S) Self bb 9,460.30±0.26 0− 1−− 0 0 0 1.22±0.03×10−20[f] See ϒ(1S) decay modes Kaon[28] K∗+ K∗− us 891.66±0.026 1⁄2 1− 1 0 0 ~7.35×10−20[f][g] See K∗
(892) decay modesKaon[28] K∗0 K∗0 ds 895.94±0.22 1⁄2 1− 1 0 0 7.346±0.002×10−20[f] See K∗
(892) decay modesD meson[29] D∗+
(2010)D∗−
(2010)cd 2,010.25±0.14 1⁄2 1− 0 +1 0 6.9±1.9×10−21[f] D0
+ π+
or
D+
+ π0D meson[30] D∗0
(2007)D∗0
(2007)cu 2,006.96±0.16 1⁄2 1− 0 +1 0 >3.1×10−22[f] D0
+ π0
or
D0
+ γstrange D meson[31] D∗+
sD∗−
scs 2,112.3±0.5 0 1− +1 +1 0 >3.4×10−22[f] D∗+
+ γ or
D∗+
+ π0B meson[32] B∗+ B∗− ub 5,325.1±0.5 1⁄2 1− 0 0 +1 Unknown B+
+ γB meson[32] B∗0 B∗0 db 5,325.1±0.5 1⁄2 1− 0 0 +1 Unknown B0
+ γStrange B meson[33] B∗0
sB∗0
ssb 5,415.4±1.4 0 1− −1 0 +1 Unknown B0
s+γCharmed B meson† B∗+
cB∗−
ccb 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:[34]
- 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.[34]
See also
References
- ^ J.J. Aubert et al. (1974)
- ^ J.E. Augustin et al. (1974)
- ^ S.W. Herb et al. (1977)
- ^ C. Amsler et al. (2008): Charmonium States
- ^ http://pdg.lbl.gov/2010/tables/rpp2010-qtab-mesons.pdf
- ^ N. Nakamura et al. (2010): Particle listings – π±
- ^ N. Nakamura et al. (2010): Particle listings – π0
- ^ N. Nakamura et al. (2010): Particle listings – η
- ^ N. Nakamura et al. (2010): Particle listings – η′
- ^ N. Nakamura et al. (2010): Particle listings – η
c - ^ N. Nakamura et al. (2010): Particle listings – η
b - ^ N. Nakamura et al. (2010): Particle listings – K±
- ^ N. Nakamura et al. (2010): Particle listings – K0
- ^ N. Nakamura et al. (2010): Particle listings – K0
S - ^ a b N. Nakamura et al. (2010): Particle listings – K0
L - ^ N. Nakamura et al. (2010): Particle listings – D±
- ^ N. Nakamura et al. (2010): Particle listings – D0
- ^ N. Nakamura et al. (2010): Particle listings – D±
s - ^ N. Nakamura et al. (2010): Particle listings – B±
- ^ N. Nakamura et al. (2010): Particle listings – B0
- ^ N. Nakamura et al. (2010): Particle listings – B0
s - ^ N. Nakamura et al. (2010): Particle listings – B±
c - ^ a b N. Nakamura et al. (2010): Particle listings – ρ
- ^ N. Nakamura et al. (2010): Particle listings – ω(782)
- ^ N. Nakamura et al. (2010): Particle listings – φ
- ^ N. Nakamura et al. (2010): Particle listings – J/Ψ
- ^ N. Nakamura et al. (2010): Particle listings – ϒ(1S)
- ^ a b N. Nakamura et al. (2010): Particle listings – K∗
(892) - ^ N. Nakamura et al. (2010): Particle listings – D∗±
(2010) - ^ N. Nakamura et al. (2010): Particle listings – D∗0
(2007) - ^ N. Nakamura et al. (2010): Particle listings – D∗±
s - ^ a b N. Nakamura et al. (2010): Particle listings – B∗
- ^ N. Nakamura et al. (2010): Particle listings – B∗
s - ^ a b J.W. Cronin (1980)
Bibliography
- K. Namakura et al. (Particle Data Group) (2010). "Review of Particle Physics". Journal of Physics G 37 (7A): 075021. Bibcode 2010JPhG...37g5021N. doi:10.1088/0954-3899/37/7A/075021.
- M.S. Sozzi (2008a). "Parity". Discrete Symmetries and CP Violation: From Experiment to Theory. Oxford University Press. pp. 15–87. ISBN 0199296669.
- M.S. Sozzi (2008a). "Charge Conjugation". Discrete Symmetries and CP Violation: From Experiment to Theory. Oxford University Press. pp. 88–120. ISBN 0199296669.
- M.S. Sozzi (2008c). "CP-Symmetry". Discrete Symmetries and CP Violation: From Experiment to Theory. Oxford University Press. pp. 231–275. ISBN 019929666.
- C. Amsler et al. (Particle Data Group) (2008). "Review of Particle Physics". Physics Letters B 667 (1): 1–1340. Bibcode 2008PhLB..667....1P. doi:10.1016/j.physletb.2008.07.018.
- S.S.M. Wong (1998). "Nucleon Structure". Introductory Nuclear Physics (2nd ed.). John Wiley & Sons. pp. 21–56. ISBN 0-471-23973-9.
- R. Shankar (1994). Principles of Quantum Mechanics (2nd ed.). Plenum Press. ISBN 0-306-44790-8.
- K. Gottfried, V.F. Weisskopf (1986). "Hadronic Spectroscopy: G-parity". Concepts of Particle Physics. 2. Oxford University Press. pp. 303–311. ISBN 0195033930.
- J.W. Cronin (1980). "CP Symmetry Violation – The Search for its origin". Nobel Lecture. The Nobel Foundation. http://nobelprize.org/nobel_prizes/physics/laureates/1980/cronin-lecture.pdf.
- V.L. Fitch (1980). "The Discovery of Charge – Conjugation Parity Asymmetry". Nobel Lecture. The Nobel Foundation. http://nobelprize.org/nobel_prizes/physics/laureates/1980/fitch-lecture.pdf.
- S.W. Herb et al. (1977). "Observation of a Dimuon Resonance at 9.5 Gev in 400-GeV Proton-Nucleus Collisions". Physical Review Letters 39 (5): 252–255. Bibcode 1977PhRvL..39..252H. doi:10.1103/PhysRevLett.39.252.
- J.J. Aubert et al. (1974). "Experimental Observation of a Heavy Particle J". Physical Review Letters 33 (23): 1404–1406. Bibcode 1974PhRvL..33.1404A. doi:10.1103/PhysRevLett.33.1404.
- J.E. Augustin et al. (1974). "Discovery of a Narrow Resonance in e+e− Annihilation". Physical Review Letters 33 (23): 1406–1408. Bibcode 1974PhRvL..33.1406A. doi:10.1103/PhysRevLett.33.1406.
- M. Gell-Mann (1964). "A Schematic of Baryons and Mesons". Physics Letters 8 (3): 214–215. Bibcode 1964PhL.....8..214G. doi:10.1016/S0031-9163(64)92001-3.
- E. Wigner (1937). "On the Consequences of the Symmetry of the Nuclear Hamiltonian on the Spectroscopy of Nuclei". Physical Review 51 (2): 106–119. Bibcode 1937PhRv...51..106W. doi:10.1103/PhysRev.51.106.
- W. Heisenberg (1932). "Über den Bau der Atomkerne I". Zeitschrift für Physik 77 (1-2): 1–11. Bibcode 1932ZPhy...77....1H. doi:10.1007/BF01342433. (German)
- W. Heisenberg (1932). "Über den Bau der Atomkerne II". Zeitschrift für Physik 78 (3-4): 156–164. Bibcode 1932ZPhy...78..156H. doi:10.1007/BF01337585. (German)
- W. Heisenberg (1932). "Über den Bau der Atomkerne III". Zeitschrift für Physik 80 (9-10): 587–596. Bibcode 1933ZPhy...80..587H. doi:10.1007/BF01335696. (German)
External links
- Particle Data Group – The Review of Particle Physics (2008)
- Mesons made thinkable, an interactive visualisation allowing physical properties to be compared
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