Eta and eta prime mesons
| Composition |
|
|---|---|
| Statistics | Bosonic |
| Family | Mesons |
| Interactions | Strong, weak, gravitational, electromagnetic |
| Symbol | η, η′ |
| Antiparticle | Self |
| Discovered | Aihud Pevsner et al. (1961) |
| Types | 2 |
| Mass | η : 547.862±0.018 MeV/c2 η′ : 957.78±0.06 MeV/c2 |
| Mean lifetime | η: (5.0±0.3)×10−19 s, η′: (3.2±0.2)×10−21 s |
| Decays into | η : γ + γ or π0 + π0 + π0 or π+ + π0 + π− η′ : π+ + π− + η or (ρ0 + γ) / (π+ + π− + γ) or π0 + π0 + γ |
| Electric charge | 0 e |
| Spin | 0 ħ |
| Isospin | 0 |
| Hypercharge | 0 |
| Parity | −1 |
| C parity | +1 |
The eta (η) and eta prime meson (η′) are isosinglet mesons made of a mixture of up, down and strange quarks and their antiquarks. The charmed eta meson (η
c) and bottom eta meson (η
b) are similar forms of quarkonium; they have the same spin and parity as the (light) η defined, but are made of charm quarks and bottom quarks respectively. The top quark is too heavy to form a similar meson, due to its very fast decay.