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What are possible lifetimes of up/down quarks, electronic/muonic/tau neutrinos, photon, gluon?
I understand they are said to be stable, but, as I saw on wikipedia, the lower bound for the "stable" electron's mean lifetime is $4.6×10^{26}$years. Are there any bounds for the mentioned particles?

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I'm sure there are, but not going to look each one up for you at the moment (maybe later). The standard reference for these questions is the Particle Data Group: pdg.lbl.gov. The website is pretty comprehensive - it should have everything you need. But be warned: if you order the (free!) print edition of the reference book it is a real bruiser. Could easily knock somebody out with it. Or bench press. –  Michael Brown Jan 24 '13 at 4:28
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But on general grounds I could tell you that all the stable particles will have lifetime limits at least as great as the age of the universe, and possibly many orders of magnitude larger. –  Michael Brown Jan 24 '13 at 4:29
    
As a practicing particle experimenter I do own a print copy of the PDG...but I only get one about every ten years because the PDF on the website is good enough for most things. –  dmckee Jan 24 '13 at 4:48
    
@dmckee I did the stupid thing of ordering a printed copy the year before the Higgs was discovered! My supervisor gets a new copy every year. Never found out what he does with the old ones. They can't be in his office - the floor is still in one piece. :) –  Michael Brown Jan 24 '13 at 8:03
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@MichaelBrown Even worse: you got it the year before $\theta_{13}$ was measured. ::goes off muttering about the collider guys getting all the glory:: –  dmckee Jan 24 '13 at 15:27
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Here is the elementary particle table of the Standard Model

sm

Stability for these building blocks of matter is an experimental observation, with limits for the ones never seen to decay. Columns II and III have measured lifetimes, excepting the neutrinos.Z and W also have measured lifetimes.

The neutrinos have a very small mass and there is nothing with smaller mass they could decay into except each other, and that is called neutrino oscillations and have been measured.

The photon and gluon have 0 mass and cannot decay.

The u and d are bounded in lifetime by the order of 10^34years of the proton decay.

The theory of the Standard Model describes all the existing data very successfully. New theories will have to embed it and predict/give these experimental bounds.

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Thanks, you've cleared my mind about decay possibilities. –  Bodik Jan 25 '13 at 1:24
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