Eta and eta prime mesons

Eta and eta prime mesons
Composition	; η; : ≈ ; ; η′; : ≈ ;
Statistics	Bosonic
Family	Mesons
Interactions	Strong, Weak, Gravitation, 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
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.

^ ^a ^b Cite error: The named reference PDG14 was invoked but never defined (see the help page).

Composition	η : ≈ ${\textstyle \mathrm {\frac {1}{\sqrt {6}}} \left(u{\bar {u}}+d{\bar {d}}-2s{\bar {s}}\right)}$ η′ : ≈ ${\textstyle \mathrm {\frac {1}{\sqrt {3}}} \left(u{\bar {u}}+d{\bar {d}}+s{\bar {s}}\right)}$
Statistics	Bosonic
Family	Mesons
Interactions	Strong, Weak, Gravitation, Electromagnetic
Symbol	η , η′
Antiparticle	Self
Discovered	Aihud Pevsner et al. (1961)
Types	2
Mass	η : 547.862±0.018 MeV/c²^[1] η′ : 957.78±0.06 MeV/c²^[1]
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
Isospin	0
Hypercharge	0
Parity	-1
C parity	+1