Omega meson
# Omega meson

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 and mediates the nuclear force along with pions and rho mesons.

## Properties

The most common decay mode for the ω meson is $π^+$ $π^0$ $π^−$ at 89.2±0.7%, followed by $π^0$ γ at 8.34±0.26%.

| Particle name | Particle symbol | Antiparticle symbol | Quark content | Rest mass $(MeV/c^2)$ | I | J | S | C | B' | Mean lifetime (s) | Commonly decays to (>5% of decays) |
| - | - | - | - | - | - | - | - | - | - | - | - |
| Omega meson | ω (782) | Self | $(uu^¯+dd^¯)/√2$ {\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 | $π^+$ + $π^0$ + $π^−$ or $π^0$ + 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.

    $\omega =\psi _{8}\sin \theta +\psi _{1}\cos \theta$,
    $\phi =\psi _{8}\cos \theta -\psi _{1}\sin \theta$,

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 arctan⁡ 1/√2 $≈35.3^∘{\textstyle$ \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.

