pion

[ pahy-on ]

Phonetic (Standard)IPA

noun

, Physics.

the first meson to be discovered: it has spin 0 and may be positively or negatively charged or neutral; charged pions decay into a muon and a neutrino or antineutrino. : π

pion

/ ˈpaɪɒn /

physics a meson having a positive or negative charge and a rest mass 273.13 times that of the electron, or no charge and a rest mass 264.14 times that of the electron

pion

/ pī′ŏn′ /

A meson occurring either in a neutral form with a mass 264 times that of an electron and a mean lifetime of 8.4 × 10 ^-17 seconds or in a positively or negatively charged form with a mass 273 times that of an electron and a mean lifetime of 2.6 × 10 ^-8 seconds. The pion was once believed to be the particle that mediates the strong force , which holds nucleons together in the nucleus; it is now believed that the gluon is the mediator particle. Pions do interact with nucleons, however, and are able to transform neutrons into protons and vice versa.
Also called pi-meson
See Table at subatomic particle