Pion

Subatomic particle; lightest meson

In particle physics, a pion (PIE-on) or 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.

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