pion(redirected from PIONA)
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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.
[Contraction of pi meson.]
(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
[C20: from Greek letter pi1 + on]
any of the three lightest mesons, having positive, negative, or neutral electric charge and spin of zero.