Meson production not originating from a collision

Question

Does anyone know a process that produces mesons other than through collisions from particle accelerators and cosmic ray experiments?

Thanks DaPhys

Answer 1

All mesons are unstable and most have quite short half-lives even by particle physics standards, so they are only to be found (as on-shell particles¹) in the presence of energetic events. And if you look closely enough the process that creates them is essentially² always one of banging two particles together pretty hard.

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¹ That is, I am excluding virtual particles from the discussion.

² I'm ignoring Hawking radiation and related processes as possible sources here. Not sure that this is entirely fair, but I can't speak authoritatively on that subject.