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Although it is definitely not simple, there are many reasons to consider that baryon number can be violated, for example:

  • during baryogenesis (just after Big Bang) there was created more matter than antimatter,
  • hypothetical Hawking radiation (black holes) can finally turn any matter (mainly baryons) into massless radiation (photons),
  • some GUT models require proton decay: https://en.wikipedia.org/wiki/Proton_decay ,
  • while charge conservation is guarded by Gauss law, there is nothing like that for baryon number.

Sure, the search for proton decay in huge room temperature water tanks was unsuccessful. However, if proton can be destroyed, it would require relatively huge energy – the assumption that it can spontaneously thermally localize on a single proton in room temperature water might be just wrong (?)

In contrast, baryogenesis and Hawking radiation examples suggest that really extreme conditions would be necessary to destroy a proton (like temperature). So another candidate might be LHC, but if happening in tiny amounts, the calorimetry has no chance to catch it, and to consider it in Monte Carlo we would need the exact parameters … is proton decay considered for LHC?

More important candidate as environment with the most extreme conditions is the center of neutron star. There are real issues with understanding the huge amounts of energy released in gamma-ray bursts – from Wikipedia: “The means by which gamma-ray bursts convert energy into radiation remains poorly understood".

Or ultraluminous X-ray sources, especially the M82 X-2: pulsar radiating ~10 million times more energy than our sun, according to Wikipedia: "shining about 100 times brighter than theory suggests something of its mass should be able to".

Hypothetically, reaching extreme conditions to start statistically essential “baryon burning” (total matter -> energy conversion, >100x more energy density than from fusion) in the center of neutron star, might help explaining these extreme energy sources.

So I wanted to ask if proton/neutron decay is considered in neutron star models? Should it?

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One has to clarify the meaning of "decay" as far as protons go.Here is a proton decay diagram in GUTS:

enter image description here

Notice that what is really disappearing is two quarks going into an antidown and an e+, to get a total baryon number of zero.

This type of proton disappearance has no need of high temperatures as it is inherent in the couplings that the theory proposes. At the moment the experimental limit is very small,~10^32 years, while supersymmetry, for example predicts 10^39 and GUTs 10^34 .

What you are talking about with your

really extreme conditions would be necessary to destroy a proton (like temperature).

is being studied in the LHC, it is called a quark gluon plasma, where all protons have disappeared and one is left with a soup of quarks, antiquarks and gluons. But baryon number is conserved in the quark gluon plasma, unless one of the disappearances of quarks ( as in figure)is included in the theory for the quark gluon plasma. The probability of this would be affected by the mass of the X (leptoquark) , but away from the resonance more energy/temperature would not make a difference .

If leptoquarks exist and their mass measured, one might try checking astrophysical data for specific energy electrons/leptons associated with collinear gamma pairs ( pi0s) for example. This would be similar to checking for antiproton proton annihilation signals for antimatter galaxies. It would still depend on the coupling measurable in accelerator experiments. Without specific information astrophysical observations are not the best laboratory for detecting new particles.

They are searching for lepto quarks at the LHC and if the new linear collider (ILC) is ever built it is one of its main projects.

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  • $\begingroup$ Thank you, I understand the short answer to my question in "no". However, it means there is still a real problem with e.g. M82 X-2: "shining about 100 times brighter than theory suggests something of its mass should be able to" - so what are the official hypothetical explanations of such enormous energy source? (not violating baryon number conservation) en.wikipedia.org/wiki/M82_X-2 $\endgroup$ – Jarek Duda Jan 28 '17 at 15:02
  • $\begingroup$ the models of physics change as time goes on and new data from experiments arrive. I was just pointing out that it is not possible to get definitive answers from astrophysical data. It works the other way around. Obviously if existing astropysical models do not fit observations, new models must be devised. Maybe baryon number violation will be playing a role, but current particle theories and data do not offer such extrapolations. $\endgroup$ – anna v Jan 28 '17 at 15:45

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