What are the lifetimes of the known particles?

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Offline jeffreyH

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What are the lifetimes of the known particles?
« on: 17/03/2016 20:08:43 »
I am specifically looking for particles with lifetimes akin to that of the proton. I know that a lot of particles decay quickly but how many persist?

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Offline chiralSPO

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Re: What are the lifetimes of the known particles?
« Reply #1 on: 17/03/2016 20:15:29 »
As far as I know, only protons, electrons, and photons are stable in isolation for long periods of time (more than an hour). Presumably antiprotons and antielectrons have the same half-lives, though they may not stick around very long in our world for other reasons (annihilation)...

Neutrons have a half-life of about 10 minutes, and muons have a half-life of a few milliseconds. I think the more exotic ones have even shorter half-lives...

Neutrinos are a whole different kettle of fish, what with their oscillations and all--I'm not sure whether to say they are very stable (appearing in one form or another for very long periods of time), or very unstable (changing between forms very quickly).

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Offline evan_au

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Re: What are the lifetimes of the known particles?
« Reply #2 on: 18/03/2016 09:06:39 »
If there is a Graviton (and most physicists think there should be), then it should be stable, or else gravity will have a limited range.

If there is a "Dark Matter Particle", it could be stable.... We just have to discover it, first!

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Offline jeffreyH

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Re: What are the lifetimes of the known particles?
« Reply #3 on: 18/03/2016 12:53:49 »
Since gluons are short range then the graviton should not act like a gluon except under extreme conditions. This should indicate that in most circumstances the gravitational field does not beget gravity.

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Offline evan_au

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Re: What are the lifetimes of the known particles?
« Reply #4 on: 19/03/2016 00:17:02 »
Quote from: chiralSPO
Neutrinos are a whole different kettle of fish, what with their oscillations and all...
Neutrinos are described as being in a superposition of three states - they are all three at once, but in different ratios at different points in space.

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Offline jeffreyH

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Re: What are the lifetimes of the known particles?
« Reply #5 on: 19/03/2016 01:12:21 »
Quote from: chiralSPO
Neutrinos are a whole different kettle of fish, what with their oscillations and all...
Neutrinos are described as being in a superposition of three states - they are all three at once, but in different ratios at different points in space.

That is why I stopped studying particles. It just got so confusing.