pi meson

noun

noun

Etymology From pi (“π”) + meson.

Dated, Formal A pion, a type of meson.

There were also particles no one had predicted that just appeared. Five of them […, i]n order of increasing modernity, […] are the neutrino, the pi meson, the antiproton, the quark and the Higgs boson.2012 March-April, Jeremy Bernstein, “A Palette of Particles”, in American Scientist, volume 100, number 2, page 146:

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