Omega meson

Omega meson

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

The omega meson () 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 at 89.2%±0.7%, followed by at 8.34%±0.26%.

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	(782)	Self	$\frac{u\overline{u}+d\overline{d}}{\sqrt{2}}$	782.66 ± 0.13	0−	1−−	0	0	0	(7.58±0.11)×10−23 s	++ or +

The quark composition of the meson can be thought of as a mix between , and states, but it is very nearly a pure symmetric – state. This can be shown by deconstructing the wave function of the into its component parts. We see that the and 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 meson is nearly a pure symmetric – state.

See also

• List of mesons
• Quark model
• Vector meson