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Preferred term

pion  

Definition

  • In particle physics, a pion (or a pi meson, denoted with the Greek letter pi : π) is any of three subatomic particles : π⁰, π⁺, and π⁻. Each pion consists of a quark and an antiquark and is therefore a meson. Pions are the lightest mesons and, more generally, the lightest hadrons. They are unstable, with the charged pions π⁺ and π⁻ decaying after a mean lifetime of 26.033 nanoseconds (2.6033×10⁻⁸ seconds), and the neutral pion π⁰ decaying after a much shorter lifetime of 85 attoseconds (8.5×10⁻¹⁷ seconds). Charged pions most often decay into muons and muon neutrinos, while neutral pions generally decay into gamma rays. (Wikipedia, The Free Encyclopedia, https://en.wikipedia.org/wiki/Pion)

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http://data.loterre.fr/ark:/67375/MDL-Q88V7KGJ-M

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