Le 27/10/2018 à 18:50, Phillip Helbig (undress to reply) a écrit :
I'm now at a cosmology conference:
https://indico.cern.ch/event/736594/overview

One reason to go to a conference is to hear about interesting things one
might have missed. For me, probably the most interesting talk was the
penultimate one, an update on these publications concerning a novel
dark-matter candidate:

https://arxiv.org/abs/1202.0560
https://arxiv.org/abs/1311.1627
http://iopscience.iop.org/article/10...6/496/1/012023
https://arxiv.org/abs/1801.04206


Those papers do not show any physical evidence. The common author in all
papers is Jarah Evslin, working in Peking.

https://arxiv.org/abs/1202.0560 says:

We propose a model of dark matter: galaxy-sized 't Hooft-Polyakov
magnetic monopoles

OK. The only evidence is presented in:
https://arxiv.org/abs/1801.04206. This paper shows a simulation for
"Spiked monopoles" done in some computer. According to the authors:
quote
Dark matter halos grow by merging. This merging requires them to be
attractive, but the simplest manifestation of monopole dark matter is
repulsive.
end quote

!!!

quote
If the magnetic repulsion is sufficiently weak, then it can be overcome
by gravity. However fitting parameters in the simplest model [1] one
finds that v â¼ 1014 GeV and so the magnetic repulsion is stronger than
gravitational attraction by nearly 10 orders of magnitude. In the spiked
monopole model, the gravitational repulsion is reduced. The crudeness of
our numerical simulations and initial conditions makes it difficult to
quantify the repulsion, however it clearly is not reduced by the
required 10 orders of magnitude.
end quote
------------------------------------------------------------------
http://iopscience.iop.org/article/10...6/496/1/012023
https://arxiv.org/abs/1311.1627

Same author, slightly different presentation, similar arguments. Both
papers are almost the same.

quote
Unfortunately these monopoles repel and so the charge Q 1 halos are
unstable. This may rule out our model. Then again, protons repel but
visible matter is mostly made of protons, as the repulsion at small
distances is canceled by neutrons and at large distances is screened by
electrons. The monopoles only repel at long distances. So what are the
analogs of the electrons? Electrons carry the opposite charge from
protons but cannot annihilate with protons as they carry a flavor
quantum number and the lightest state for a decay product, the neutron,
is too massive for the decay to be kinematically allowed. Similarly such
a flavor quantum number for the monopoles is an automatic consequence of
our fermionic couplings. The masses of the various flavors of monopoles
can be adjusted by choosing the Yukawa couplings. We propose to include
light antimonopoles of a different flavor which screen the long distance
repulsion of our monopoles. If such a screening cannot be made to work,
our proposal will be excluded.
end quote

Let's see then...

They have to first find out the "electrons" that would screen out the
repulsion between those galaxy sized monopoles.

All this is interesting, yes, but it is very difficult to gauge if there
is any connection with reality at this stage. Mathematics is an infinite
forest, and it is very easy to lose your way in the equation undergrowth...

Obviously too, I am in NO WAY able to follow precisely those papers, and
can only look at the conclusions.

jacob