Omega meson

The omega meson (Template:Subatomic particle) 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 Template:Subatomic particleTemplate:Subatomic particleTemplate:Subatomic particle at , followed by Template:Subatomic particleTemplate:Subatomic particle at .

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)
Omega meson	Template:Subatomic particle(782)	Self	$\frac{u\overline{u}+d\overline{d}}{\sqrt{2}}$	782.66 ± 0.13	0−	1−−	0	0	0		Template:Subatomic particle+Template:Subatomic particle+Template:Subatomic particle or Template:Subatomic particle+Template:Subatomic particle

The quark composition of the Template:Subatomic particle meson can be thought of as a mix between Template:Subatomic particleTemplate:Subatomic particle, Template:Subatomic particleTemplate:Subatomic particle and Template:Subatomic particleTemplate:Subatomic particle states, but it is very nearly a pure symmetric Template:Subatomic particleTemplate:Subatomic particle–Template:Subatomic particleTemplate:Subatomic particle state. This can be shown by deconstructing the wave function of the Template:Subatomic particle into its component parts. We see that the Template:Subatomic particle and Template:Subatomic particle mesons are mixtures of the SU(3) wave functions as follows.

$\omega ={\psi }_8\sin \theta +{\psi }_1\cos \theta$,

$\varphi ={\psi }_8\cos \theta -{\psi }_1\sin \theta$,

where

$\theta$ is the nonet mixing angle,

${\psi }_1=\frac{u\bar{u}+d\bar{d}+s\bar{s}}{\sqrt{3}}$ and

${\psi }_8=\frac{u\bar{u}+d\bar{d}-2s\bar{s}}{\sqrt{6}}$.

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

See also

• List of mesons
• Quark model
• Vector meson