[Kevmo]

Mesons decay into muons.

https://freerepublic.com/focus/f-chat/3948201/posts?page=1#1

[TexasGator]

“Mesons decay into muons.”

wiki:

All mesons are unstable, with the longest-lived lasting for only a few hundredths of a microsecond. Heavier mesons decay to lighter mesons and ultimately to stable electrons, neutrinos and photons.