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(I am not a cosmologist and instead currently working on a master thesis about Feynman integrals, so sorry if I'm missing something obvious. This question is merely out of interest.)

I was wondering whether there are people working on Higgs cosmology and if they are not, then why are they not? Is there some clear prediction which contradicts observations? I have seen a lot of theories mentioned with 'dark matter coupled to Higgs', but rarely that Higgs itself could be dark matter.

For clarity, with 'Higgs cosmology' I'm referring to the following idea I have encountered a few times in conversation but never seen in my Cosmology course or in media like Wikipedia:

  • The Higgs particle has a vacuum expectation (after symmetry breaking etc.) but also has interactions with mass. Therefore, the actual value of the Higgs field in the neighbourhood of mass may differ significantly from the vacuum expectation.
  • This means that near large masses (e.g. a star) one would expect the Higgs field to have a significantly different expectation depending on the distance from the star, becoming the vacuum expectation in the large-distance limit.
  • This means that stars could have an effective 'halo' from the Higgs field. If this halo is short-range one would not expect any cosmological relevance, but if it is sufficiently long-ranged it will have effect as follows.
  • Two nearby stars will both have a halo, so now the interactions are not only star -- star (gravity) but also halo -- star, star -- halo and halo -- halo. The halo -- star attraction might contribute to dark matter, while the halo -- halo interaction is even more unclear and might provide a very long-range force hence either contributing or working against dark energy.

(One remark: If the halo is indeed sufficiently long-ranged then the results from CERN have to be taken a bit more nuanced, for the setup at CERN can make a matter-vacuum and make it dark, but can not avoid being inside the Higgs-halo of all the matter nearby.)

Again, I am not a cosmologist so I wouldn't notice gaping holes in the theory. Could someone please explain why this theory is not popular?

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  • $\begingroup$ "the following idea I have encountered a few times in conversation" Do these people know how to calculate the magnitude of their proposed effect? $\endgroup$ Oct 22, 2020 at 10:04
  • $\begingroup$ @mitchellPorter No, this was in a conversation with string theorists and/or particle theorists, none of us have any clear ties with cosmology. $\endgroup$ Oct 22, 2020 at 10:28
  • $\begingroup$ Something doesn't make sense here. Calculating a supposed shift in the higgs VEV, due to interactions with mass, is not a problem in cosmology, it's a problem in quantum field theory... I doubt very much that this is a real thing. The "Higgs force" for anything other than the top quark should be negligible, and even there is negligible at anything other than very short distances. Also, if the higgs VEV was different near celestial bodies, the masses e.g. of electrons should be different and it would show in the spectroscopic properties of atoms. $\endgroup$ Oct 22, 2020 at 14:10
  • $\begingroup$ There is the question of why we apparently don't feel the higgs VEV as an overwhelming source of gravity, but that is just one component of the cosmological constant problem and whether vacuum energy gravitates. $\endgroup$ Oct 22, 2020 at 14:11
  • $\begingroup$ @mitchellPorter Okay, so the point is that we already know that the "Higgs force" would be extremely short-distance? In that case, is any Dark Matter theory where dark matter relies on interactions with the Higgs field doomed because those theories can not build a substantional halo? $\endgroup$ Oct 22, 2020 at 15:28

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Scalar field cosmology is widely studied (under the name scalar tensor theories) to answer several questions of cosmology. Higgs field is particularly used to drive the expansion of spacetime in the early epochs (Higgs Inflation). It has been also used to study the dark sector.

Higgs particle itself cannot be a dark matter candidate for a simple reason as it decays very quickly. The Dark matter on the other hand should be a stable particle and should not interact through electromagnetism (both conditions wont apply to higgs particle themselves). We can however introduce new force carriers and try to explain dark matter.

Higgs can only act as a gravitational force (like dark matter particles) in the very early epochs of the universe where, $H$ the Hubble rate is much larger than 246 GeV.

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