Can proton/neutron decay be avoided in some conditions?

[Suekdccia]

TL;DR

Can the decay of neutrons and protons (assuming it happens, as it is not proven) be avoided in some cases (like certain types of neutron stars, white dwarfs or other systems)?

I was wondering whether the decay of neutrons and protons (if they happen to be able to decay, as it is predicted by some GUTs) could be avoided in some cases.

Let's begin with neutrons:

In principle neutrons have a very short time when they are isolated (around 10 minutes) and they suffer beta decay, but because of electron degeneracy pressure, it is heavily supressed in a neutron star (What stabilizes neutrons against beta decay in a neutron star?).

So, if this happens, then, shouldn't neutron stars be "safe" from the decay of neutrons and protons (in case there is proton decay, as there are almost no protons but mainly neutrons)?

I read an article, A Dying Universe: The Long Term Fate and Evolution of Astrophysical Objects, where they describe that as neutron stars would have protons (for example, they would have ordinary matter in their surface) the protons would decay, decreasing the degeneracy pressure on the neutrons and allowing bets decay to occur. But, I was thinking: Is it impossible for a pure neutron star to exist? So that the the degeneracy pressure would be maintained by electrons (held together by gravity and pressure)?

Then we go for the protons:

Could there be some situations in which, even if protons could decay, this could be somehow avoided? For example, if there was a white dwarf with a high density of electrons, could they maintain the degeneracty pressure and supress proton decay? Or perhaps a very high angular momentum, so that it would cause some kind of force or pressure (like a high centripetal force) that would keep a similar degeneracy pressure that would keep protons from decaying?

If not, can you think of any other ways? Or proton decay, if it occurs, is unavoidable and therefore neutron decay as well?

 

[mfb]

Assuming proton decay is possible, the energy released is too large to stabilize them in any way. Neutrons can decay via equivalent methods then, their environment doesn't matter either.

 

[Hornbein]

The cores of neutron stars aren't pure neutrons. They have a small percentage of protons and electrons in an equilibrium state. The idea that neutron star cores are pure neutrons [neutronium] is incorrect. This idea appears in science fiction, maybe that's how so many got this idea. The decay is inhibited by the extreme pressure, but still happens.

Neutron star cores are superfluid and superconductive. The superconductivity comes from the protons! Note that neutron stars are so dense it is possible that the proton density is the highest found in the Universe, but I have never tested/confirmed this.

I suppose that decay is also inhibited in white dwarfs, but not to such a degree.

It is possible that the central core of a neutron contains kaons or even a quark plasma. It's difficult to be sure because there is no good way to measure the diameter of a neutron star, so we don't know exactly what the density is.

 

[ohwilleke]

Even if protons did decay, the rate would be so low that it is irrelevant. See Super-Kamiokande Collaboration, "Search for proton decay via p→μ+K0 in 0.37 megaton-years exposure of Super-Kamiokande" arXiv:2208.13188 (August 28, 2022).

The universe is about 1.37 x 10^10 years old. This limitation means that we would expect that not more than about 2 in 10^23 protons would have decayed so far, everywhere in the universe, for all time. And, of course, this is just a lower bound on the proton lifetime.

The hypothesis that the proton is completely stable seems far more plausible, and is supported by solid theoretical considerations. No GUT theory so far has ever held up to scrutiny.