Omega meson

Meson that is a superposition of an up quark–antiquark and a down quark–antiquark pair

Omega meson
Composition	${\textstyle \approx {\frac {u{\bar {u}}+d{\bar {d}}}{\sqrt {2}}}}$
Statistics	Bosonic
Family	Mesons
Interactions	Strong, weak, electromagnetic, gravity
Symbol	ω
Antiparticle	Self
Theorized	Yoichiro Nambu^[1] (1957)
Discovered	Lawrence Berkeley National Laboratory (1961)^[2]^[3]
Types	1
Mass	782.66±0.13 MeV/c²
Mean lifetime	(7.58±0.11)×10⁻²³ s
Decays into	π⁺ + π⁰ + π⁻ or π⁰ + γ
Electric charge	0 e
Spin	1
Isospin	0
Hypercharge	0
Parity	−1
C parity	−1

The omega meson (
ω
) is a flavourless meson formed from a superposition of an up quark–antiquark and a down quark–antiquark pair. It is part of the vector meson nonet^[4]^[5] and mediates the nuclear force along with pions and rho mesons.

Properties

The most common decay mode for the ω meson is
π⁺

π⁰

π⁻
at 89.2±0.7%, followed by
π⁰

γ
at 8.34±0.26%.^[6]

Particle name	Particle symbol	Antiparticle symbol	Quark content	Rest mass (MeV/c²)	I^G	J^PC	S	C	B'	Mean lifetime (s)	Commonly decays to (>5% of decays)
Omega meson^[6]	ω (782)	Self	${\textstyle {\frac {u{\bar {u}}+d{\bar {d}}}{\sqrt {2}}}}$	782.66 ± 0.13	0⁻	1⁻⁻	0	0	0	(7.58±0.11)×10⁻²³ s	π⁺ + π⁰ + π⁻ or π⁰ + γ

The quark composition of the
ω
meson can be thought of as a mix between
u

u
,
d

d
and
s

s
states, but it is very nearly a pure symmetric
u

u
-
d

d
state. This can be shown by deconstructing the wave function of the
ω
into its component parts. We see that the
ω
and
ϕ
mesons are mixtures of the SU(3) wave functions as follows.^[7]

\omega =\psi _{8}\sin \theta +\psi _{1}\cos \theta

\phi =\psi _{8}\cos \theta -\psi _{1}\sin \theta

where

\theta

is the nonet mixing angle,

\psi _{1}={\frac {u{\overline {u}}+d{\overline {d}}+s{\overline {s}}}{\sqrt {3}}}

and

\psi _{8}={\frac {u{\overline {u}}+d{\overline {d}}-2s{\overline {s}}}{\sqrt {6}}}

The mixing angle at which the components decouple completely can be calculated to be ${\textstyle \arctan {\frac {1}{\sqrt {2}}}\approx 35.3^{\circ }}$ , which almost corresponds to the actual value calculated from the masses of 35°. Therefore, the
ω
meson is nearly a pure symmetric
u

u
-
d

d
state.

References

^ Nambu, Yoichiro (April 25, 1957). "Possible Existence of a Heavy Neutral Meson". Physical Review. 106 (6): 1366–1367. Bibcode:1957PhRv..106.1366N. doi:10.1103/PhysRev.106.1366.
^ Maglić, B. C.; Alvarez, L. W.; Rosenfeld, A. H.; Stevenson, M. L. (August 14, 1961). "Evidence for a T=0 three-pion resonance". Physical Review Letters. 7 (5): 178–182. Bibcode:1961PhRvL...7..178M. doi:10.1103/physrevlett.7.178. S2CID 121570977.
^ Maglich, B. (1976). "Discovery of omega meson-first neutral vector meson: one researcher's personal account - Discovery story". Advanced Experimental Physics. 5: 79–105.
^ Gell-Mann, M. (March 15, 1961). "The Eightfold Way: A Theory of Strong Interaction Symmetry" (TID-12608). Pasadena, CA: California Inst. of Tech., Synchrotron Laboratory: 24. doi:10.2172/4008239. {{cite journal}}: Cite journal requires |journal= (help)
^ Ne'eman, Y. (August 1961). "Derivation of Strong Interactions from a Gauge Invariance". Nuclear Physics. 26 (2). Amsterdam: North-Ho lland Publishing Co.: 222–229. Bibcode:1961NucPh..26..222N. doi:10.1016/0029-5582(61)90134-1.
^ ^a ^b Zyla, P. A. (2021) [2020]. "Particle listing - ω(782)" (PDF). Particle Data Group. Retrieved June 9, 2021.
^ Amsler, C.; DeGrand, T.; Krusche, B. (August 2019). "15. Quark Model" (PDF). Particle Data Group. Retrieved 9 June 2021.

Particles in physics

Elementary

Fermions

Quarks	Up (quark antiquark) Down (quark antiquark) Charm (quark antiquark) Strange (quark antiquark) Top (quark antiquark) Bottom (quark antiquark)
Leptons	Electron Positron Muon Antimuon Tau Antitau Neutrino Electron neutrino Electron antineutrino Muon neutrino Muon antineutrino Tau neutrino Tau antineutrino

Bosons

Gauge	Photon Gluon W and Z bosons
Scalar	Higgs boson

Ghost fields

Faddeev–Popov ghosts

Hypothetical

Superpartners

Gauginos	Gluino Gravitino Photino
Others	Axino Chargino Higgsino Neutralino Sfermion (Stop squark)

Others

Composite

Hadrons

Baryons	Nucleon Proton Antiproton Neutron Antineutron Delta baryon Lambda baryon Sigma baryon Xi baryon Omega baryon
Mesons	Pion Rho meson Eta and eta prime mesons Bottom eta meson Phi meson J/psi meson Omega meson Upsilon meson Kaon B meson D meson Quarkonium
Exotic hadrons	Tetraquark (Double-charm tetraquark) Pentaquark