•   Wikis

# Η meson: Wikis

Note: Many of our articles have direct quotes from sources you can cite, within the Wikipedia article! This article doesn't yet, but we're working on it! See more info or our list of citable articles.

# Encyclopedia

(Redirected to Eta meson article)

 Eta and eta prime mesons Composition: η : $\mathrm{\tfrac{u\bar{u} + d\bar{d} - 2s\bar{s}}{\sqrt{6}}}$ η′ : $\mathrm{\tfrac{u\bar{u} + d\bar{d} + s\bar{s}}{\sqrt{3}}}$ Statistical behavior: Bosons Group: Mesons Interaction: Strong, Weak Symbol(s): η, η′ Antiparticle: Self Mass: η : 547.853 ± 0.024 MeV/c2 η′ : 957.66 ± 0.24MeV/c2 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: Integer

The eta (η) and eta prime meson (η′) are mesons made of a mixture of up, down and strange quarks and their antiquarks. The charmed eta meson (ηc) and bottom eta meson (ηb) are forms of quarkonium; they have the same spin and parity as the light eta but are made of charm quarks and bottom quarks respectively. The top quark is too heavy to form a similar meson (top eta meson, symbol ηt), due to its very fast decay.

The eta was discovered in pion-nucleon collisions at the Bevatron in 1961.

The difference between the mass of the η and that of the η' is larger than the quark model can naturally explain. This "η-η' puzzle" is resolved by instantons.