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Re: resonances in particle physics



At 09:33 PM 12/7/00 -0500, Chuck Britton wrote:
> And will someone who IS familiar with the Particle Physics use of the
term 'resonance' please comment on this 'distinction'.

I'm not sure what "distinction" we are talking about. Particle physicists
use this word in an intelligent way.

Scattering particle A off of target B is equivalent to re-radiation of A's
wave function into new directions.

Resonant scattering can be very powerful. It happens when the target has
two long-lived states separated by an energy that matches A's incident energy.

Low-Q not-very-resonant scattering occurs when the target has blurry
short-lived excited states.

One particularly interesting class of short-lived "excited states"
corresponds to the creation of short-lived subatomic particles.

Punch line: A high-Q resonance could well be the sign of creation of a
long-lived particle. So if you hear somebody say "we found a resonance"
when you expected to hear "we found a particle" now you know why.