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I know that neutrons are stable within the nucleus of an atom but free neutrons have a half-life. I couldn't find any information on neutrino half-lives.

Do neutrinos have a half-life? Since neutrinos are rarely measurable, do we have enough information to know?

CJ Dennis
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  • The Particle Data Group at LBL keeps track for the high energy physics community about the best available particle property data. If you go to http://pdg8.lbl.gov/rpp2014v1/pdgLive/Particle.action?node=S066 you will find a link to mean life/mass http://pdg8.lbl.gov/rpp2014v1/pdgLive/DataBlock.action?node=S066TMR which has a list of papers with the best available measurements for possible neutrino decay channels. As you can see there is a wide range of variation on the limits of neutrino lifetime based on different physical measurements. – CuriousOne Jul 07 '15 at 05:36
  • @CuriousOne; the link you provided seems to be invalid. –  Sep 27 '16 at 16:06

1 Answers1

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Neutrinos are elementary particles in the standard model, which model has been very successful in organizing all the data we have on elementary particle interactions in a mathematically rigorous form. In the table for elementary particles neutrinos are considered stable, in contrast to taus and muons, as quantum number and energy conservation, within the standard model hypothesis, do not allow them to decay. Thus we trust that neutrinos do not decay, otherwise the calculations would not fit the data we have on neutrinos, as they do. If they are found to decay that would show the need for a theory beyond the standard model.

Still, as CuriousOne says in the comments, there are experiments trying to find limits for neutrino decays, which are very small, and do not challenge the standard model at the moment.

Neutrinos can disappear in interactions with other elementary particles, but the timing depends on the specific interactions. They can also oscillate within the species of neutrinos, this also has been measured and slotted into the standard model, but that is a different story than decay.

anna v
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  • Maybe we should rename the neutrino "the little particle that could (surprise us)"... to be frank I find neutrinos and their oscillations a lot more interesting than the Higgs. Who knows, maybe they have some more tricks up their sleeves? – CuriousOne Jul 07 '15 at 05:49
  • What about Muon and Tau Neutrinos? The Muon and Tau particles aren't stable and they're elementary. (I tried to research that before asking without luck). – userLTK Jul 07 '15 at 05:49
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    @userLTK A muon can decay into a muon neutrino, an electron, and an electron anti-neutrino because the mass of a muon is greater than the mass of the three decay products. A muon neutrino, on the other hand, has no particles it can decay into while conserving energy, lepton number, and lepton flavor, and so it's stable. Probably. – ragnar Jul 07 '15 at 06:01
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    @ragnar: Neutrino decay into photons would violate lepton number conservation, but there is no absolute law that makes lepton number and flavor perfectly conserved, so they may be slightly violated and we just haven't been able to experimentally find that violation, yet. – CuriousOne Jul 07 '15 at 06:12
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    Hence the "probably". – ragnar Jul 07 '15 at 06:16
  • @ragnar: Probably is always a safe word in science. :-) – CuriousOne Jul 07 '15 at 07:47