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This question is what lead me to ask this. Strong force between quarks that are out of causal contact and my understanding of the standard model is that the answer is no - but the standard model isn't necessarily absolute.

Like, for example, when the strong, weak and electromagnetic forces combine at some obscenely high energy state - do solo quarks become possible?

If this article is correct, I'm guessing the answer is yes, or, at least, maybe: http://physics.aps.org/articles/v7/61 but the article is for Top Quarks.

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    $\begingroup$ Certainly there is, as the confinedness of the quarks is due to spontaneous symmetry breaking of the vacuum. This implies there is phase transition to the vacuum of unbroken symmetry. See wikipedia on the QCD vacuum. $\endgroup$ Jun 15 '15 at 20:38
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    $\begingroup$ One should add, that such a temperature is so high, that there will be lots of thermally excited quarks and anti-quarks (and gluons), so "individually stable" is not really an applicable category. $\endgroup$ Jun 15 '15 at 21:01
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One is speaking of models, which are validated at low energies and are evaluated at energies much higher than laboratory energies.

In Grand Unification of all three forces weak, strong and electromagnetic,

In the 1970's, Sheldon Glashow and Howard Georgi proposed the grand unification of the strong, weak, and electromagnetic forces at energies above 10^14 GeV. If the ordinary concept of thermal energy applied at such times, it would require a temperature of 10^27 K for the average particle energy to be 10^14 GeV.

These condition can theoretically happen at the very early universe in a cosmological model, as the Big Bang model.

What does unification mean? That the exchanged bosons are essentially all one boson and the spin 1/2 particles are one "particle" described by the group representation structure. In this sense, in the extreme conditions of the early universe if electrons can be then called free, so will quarks be free.

They cannot be free in laboratory or cosmic ray situations.

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  • $\begingroup$ You say GUT means that all gauge bosons are one, but even in electroweak, we have four. And wouldn't a GUT require the exact same number of bosons as what it unifies, as a low energy limit would be the SM? $\endgroup$
    – Omry
    Jun 16 '15 at 4:08
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    $\begingroup$ @Omry Note the quotation marks, they are "one" as they have zero mass but the quantum numbers that represent them are there in the appropriate group representation (strangeness, beauty ,...) . $\endgroup$
    – anna v
    Jun 16 '15 at 4:48

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