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What would happen if the half-life of a neutron was much more less than it is now? How could this affect the nuclei?

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The halflife of the neutron is set by three things (more or less):

  1. the mass difference between the neutron and the proton,
  2. the number (two) of light particles that accompany the decay and
  3. the strength of the weak interaction.

Changing number (3) effects the lifetime of all weak mediated processes, but all of them in the same sense.

Changing (1) reconfigures the entire table of the nuclides.

Changing (2) requires a complete re-write of our understanding of small scale physics and could do essentially anything.

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  • $\begingroup$ Please could whoever downvoted this, add some comment. Question: would altering the W mass also do the job? $\endgroup$ – Rob Jeffries Nov 4 '15 at 22:33
  • $\begingroup$ @rob I would have lumped that into changing the strength of the weak interaction, but the short answer is yes.. Make it lighter to increase the low energy coupling. $\endgroup$ – dmckee --- ex-moderator kitten Nov 4 '15 at 23:55
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For the lifetime of the neutron to be different, the weak interaction coupling constant would be different. As far as nuclei are concerned the unstable ones with beta decays would have different lifetimes. In general all weak interaction mediated decays would have different lifetimes.

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  • $\begingroup$ Could you not just change the W mass, or is that dependent on the coupling constant? $\endgroup$ – Rob Jeffries Nov 4 '15 at 20:30
  • $\begingroup$ @RobJeffries The W also decays. I guess if the W and Z masses were different again the lifetimes would be different ( less off mass shell for neutrons, or more). If we ever get a theory of everything we might have less measurement constants entering the Lagrangian. AFAIK yes, a change in the gauge bosons of the weak interaction would have the same affect as far as observations of lifetimes go. $\endgroup$ – anna v Nov 5 '15 at 4:23
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Ryan is correct. In addition I would point to beta decay, in one form of which a neutron is transformed into a proton, inside the nucleus. This is called $\beta^-$ decay and is accompanied by the emission of an electron $e^-$ by the affected nucleus.

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The half life of a lone neutron is only fourteen minutes. When a lone neutron decays, it decays into a proton, electron, and electron neutrino. However, a neutron bound to a proton is relatively stable, so a neutron in an atomic nucleus would not decay.

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  • $\begingroup$ Well, changing physics so that the neutron would decay much faster also means that the strong/weak force physics in the nucleus is changing as well. $\endgroup$ – Jon Custer Nov 4 '15 at 19:30

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