How do mesons not self-destruct?

[tinypositrons]

Hello physicists,

I was speaking to my friend about mesons when I realized that surely a meson would annihialate at creation due to the fact that it has a quark and anti-quark. I know it doesn't, but I'm wondering why. Clarrification on this would be great.

Thanks,
Joe

 

[Bill_K]

Well they do. Depending of course on what you mean by "annihilation".

All mesons decay. Most mesons consist of a quark and antiquark of different types, although some do contain a quark and antiquark of the same variety (see "quarkonium").

But remember that annihilation is not an instantaneous process, e.g. an electron-positron pair can form a bound state, positronium, which lasts for ~ 10^-10 sec (that's a pretty long time!) before decaying.