pion

pi·on  (pn)

n.

Any of the three least massive mesons having a positive, neutral, or negative electric charge. The charged pions have a mass 273 times that of an electron and a mean lifetime of 2.6 × 10^-8 second and the neutral pion has a mass 264 times that of an electron and a mean lifetime of 8.4 × 10^-17 second. Also called pi meson. See Table at subatomic particle.

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[Contraction of pi meson.]

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pion [ˈpaɪɒn], pi meson

n

(Physics / General Physics) 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

[from Greek letter pi¹ + on]

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pion  (pn)

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.

Thesaurus

Noun

1.

pion - a meson involved in holding the nucleus together; produced as the result of high-energy particle collision pi-meson meson, mesotron - an elementary particle responsible for the forces in the atomic nucleus; a hadron with a baryon number of 0