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I have recently learn and read some articles about the false vacuum in quantum fields theory.
I wanted to know why scientists think that Higgs field could be in a metastable state instead of vacuum state like the others fields.
Can anyone explain me why ?

Vacuum state are when fields or particles have their lowest energy level possible
Metastable state are when the fields or particles reach a lower level but not the lowest one.
Am i right ?
Thank in advance, Creekorful

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    $\begingroup$ I deleted my comment about the boson, but that might not be what physics guy meant. I think you should expand your post to say a bit about what you think metastable and vacuum states are and how they differ, just a short summary including the VEV of other fields versus that of the Higgs. Also you should cite your source for the quote... why scientists think that Higgs field could be in a metastable state $\endgroup$ – user108787 Nov 3 '16 at 17:54
  • $\begingroup$ I can't find the article name. But there is a video that state the same thing : youtube.com/watch?v=ijFm6DxNVyI. The video say that every fields want to reach their ground state : the vacuum state. Except for the higgs field $\endgroup$ – americium1997 Nov 3 '16 at 17:56
  • $\begingroup$ I found it extremely curious that just a few days ago I run into this video: youtube.com/watch?v=ijFm6DxNVyI Where they talk about false vacuum in QFT in a really divulgative way. Maybe it can help here. $\endgroup$ – P. C. Spaniel Nov 3 '16 at 17:57
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I have recently learn and read some articles about the false vacuum in quantum fields theory.

Here is a definition:

In quantum field theory, a false vacuum is a metastable sector of space that appears to be a perturbative vacuum, but is unstable due to instanton effects that may tunnel to a lower energy state

falsevacuum

A scalar field φ in a false vacuum. Note that the energy E is higher than that in the true vacuum or ground state, but there is a barrier preventing the field from classically rolling down to the true vacuum. Therefore, the transition to the true vacuum must be stimulated by the creation of high-energy particles or through quantum-mechanical tunneling.

The existence of a false vacuum is a hypothesis that some theories may use, but it is not the Higgs mechanism.

I wanted to know why scientists think that Higgs field could be in a metastable state instead of vacuum state.

The Higgs field is not metastable in the sense of a false vacuum. It is dependent on the energy available and is symmetric for high enegies of the interactions involved ( order of 100 GeV) , and broken for lower energies.

An example of symmetry breaking analogous to what happens with the Higgs field:

higgs field

Spontaneous symmetry breaking simplified: – At high energy levels (left) the ball settles in the center, and the result is symmetrical. At lower energy levels (right), the overall "rules" remain symmetrical, but the "Mexican hat" potential comes into effect: "local" symmetry is inevitably broken since eventually the ball must roll one way (at random) and not another.

At each energy the vacuum is stable, it is not a false vacuum. The difference between the vacuum for the other fields , like the electron field and the photon field, is in the vacuum expectation value.

In quantum field theory the vacuum expectation value (also called condensate or simply VEV) of an operator is its average, expected value in the vacuum.

For all other particles the vacuum expectation value in the standard model is zero, for the Higgs it is 246GeV, at the broken state .

The conditions for symmetry existed at the beginning of the universe, according to the Big Bang model. The symmetry is broken at about 10^-10 seconds in the life of the universe (temperatures correspond to 100 GeV) and the Higgs field acquires the large vev.

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    $\begingroup$ Hi Anna! These are all just basic definitions which could be found in QFT textbooks. What I would really like to learn (especially, from an experimentalist like you), and I deduce from the question that OP would like to learn it also, is what kinds of the current experimental data are in favor of metastability of the electroweak vacuum (all of it?) and what effects will metastability have on the fate of the universe. $\endgroup$ – Prof. Legolasov Nov 5 '16 at 15:45
  • $\begingroup$ Also, metastability is not the same as spontaneous symmetry breaking! The question is: why has our universe chosen a metastable vacuum state (which, from what I know, is many orders of magnitude more shallow than the true vacuum) instead of the stable one during symmetry breaking? Maybe it has something to do with inflation? Please correct me if I am wrong, I am no expert at this field, but I would like to know more. $\endgroup$ – Prof. Legolasov Nov 5 '16 at 15:52
  • $\begingroup$ @SolenodonParadoxus I do not know of experiments looking for metastability of the higgs field vacuum. there are speculation to be checked with cosmological models I guess, physics.aps.org/articles/v8/108 . seems that more accurate measurements of the top mass and the higgs boson mass might contribute according to the article linked. $\endgroup$ – anna v Nov 5 '16 at 16:13
  • $\begingroup$ @SolenodonParadoxus Also I stress that the Higgs field is stable, symmetry breaking is not metastability, which seemed to me to be the confusion. The possible metastability of the Higgs field comes from calculations as in the link, but 1.3 sigma difference is identical to noise , no signal, in particle physics, which deals with five sigma significances to accept a measurement. $\endgroup$ – anna v Nov 5 '16 at 16:20

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