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For an ordinary superconductor such as Lead, charge supercurrent gives rise to a magnetic field around the whole material for low enough currents. At large enough currents, the superconductor will either return to the normal phase, or will screen part of the magnetic field from the supercurrent through vorticies. Depending on which effect occurs, the superconductor would be considered type I or type II.

Recently I saw the article by Krishna Rajagopal and Frank Wilczek The Condensed Matter Physics of QCD. I am totally unfamiliar with QCD, but this got me thinking about color superconductors. In particular, a color-charged supercurrent would have to give rise to some sort of static/DC color or gluon field. However, I presume the strong interaction would mean such a static color field would cost huge amounts of energy, and would immediately give rise to either vorticies or some other mechanism to screen it. Alternatively, it could be that only color-neutral supercurrents/cooper pairs can exist because of the aforementioned energy cost.

So I want to ask, in a color superconductor can a color supercurrent possibly exist? If so, how does the rest of the superconductor respond?

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    $\begingroup$ You are probably barking up the wrong tree. The long range magnetic field outside a superconductor cannot have an analog in QCD. There cannot be long range color fields in vacuum (our outside). There are subtle phenomena in exceptional, recondite media bypassing infrared slavery, but residual macroscopic long range color fields in vacuum are an impossibility. $\endgroup$ – Cosmas Zachos Dec 28 '18 at 21:42
  • $\begingroup$ I was thinking of possible color superconductors in neutron stars, certainly that would be considered an exceptional media? Forgive me, I'm not terribly familiar with QCD $\endgroup$ – KF Gauss Dec 29 '18 at 23:47
  • $\begingroup$ QCD fields are strong at low energies and weak at high energies, such as inside neutron stars... the intuition is the opposite to that one gets in electromagnetic fields... $\endgroup$ – Cosmas Zachos Dec 29 '18 at 23:58
  • $\begingroup$ @If the fields are weak at high energy, wouldn't that make it more likely for a static field? I trust you are completely right, so if you could write a comprehensive answer from the perspective of electromagnetic superconductors that would be very helpful $\endgroup$ – KF Gauss Dec 30 '18 at 0:45
  • $\begingroup$ Sorry, comprehensive answer sounds like a tutorial... There are superb books, reviews, etc of plain superconductivity, QCD, etc... $\endgroup$ – Cosmas Zachos Dec 30 '18 at 1:20

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