color superconductivity

[Shima]

Is Color Superconducting phase really superconductor? What would be the meaning of " Color Conductivity " or " Color Resistivity " there ?

[Schrödinger's hat]

...I don't even...

Uhmm, some kind of freaky exotic matter where some quarks are free to travel and carry color? I have absolutely no idea how one would interact with this.

[questionposter]

Is Color Superconducting phase really superconductor? What would be the meaning of " Color Conductivity " or " Color Resistivity " there ?

 

Here's a link with some info

http://en.wikipedia.org/wiki/Color_superconductivity

 

I think quarks also carry something called color-charge, which is that they have 3 different types of attractive/repulsive forces as opposed to two.

[Shima]

To Schrodinger's hat and questionposter,

 

Thanks for your replies.

 

I couldn't find anything about the " color resistivity " concept through the scientific articles and also in Wikipedia.

 

Imagine that we have the definition of "color conductivity" with the flow of (colorful) quarks in a quark matter system.

 

Now we should be able to describe something like insulators or conductors.

 

What kind of interaction can oppose the quarks flow?

 

Anyway I think these conceptions are not physically meaningful, whilst we don't have any gauge invariant

 

quantity as the color resistivity or color current (which in color superconductors must be a supercurrent).

 

Am I right?

[Schrödinger's hat]

To Schrodinger's hat and questionposter,

 

Thanks for your replies.

 

I couldn't find anything about the " color resistivity " concept through the scientific articles and also in Wikipedia.

 

Imagine that we have the definition of "color conductivity" with the flow of (colorful) quarks in a quark matter system.

 

Now we should be able to describe something like insulators or conductors.

 

What kind of interaction can oppose the quarks flow?

 

Anyway I think these conceptions are not physically meaningful, whilst we don't have any gauge invariant

 

quantity as the color resistivity or color current (which in color superconductors must be a supercurrent).

 

Am I right?

 

I guess one could go directly to superconductivity without having an analogue of conductivity.

If you were to get the whole thing (whatever type of thing we're talking about) in a single quantum state, then pushing another charge carrier into it would increase the potential of the one (which would be indistinguishable) on the other end.

The problem is in trying to conceive what kind of system we're even talking about. I admit I'm almost completely lost when it comes to QCD, but as far as I knew gluons could only act over tiny distances, and non-white collections of quarks aren't stable.

Edited September 15, 2011 by Schrödinger's hat

[questionposter]

I guess one could go directly to superconductivity without having an analogue of conductivity.

If you were to get the whole thing (whatever type of thing we're talking about) in a single quantum state, then pushing another charge carrier into it would increase the potential of the one (which would be indistinguishable) on the other end.

The problem is in trying to conceive what kind of system we're even talking about. I admit I'm almost completely lost when it comes to QCD, but as far as I knew gluons could only act over tiny distances, and non-white collections of quarks aren't stable.

 

Wait, why does there even need to be gluons for single protons if the quarks respond to each other's color charge attractively and always have attractive charges? I guess two are down and one is up, but its still a lets say Xcharge and Ycharge and Zcharge which are all attracted to each other, so why does there need to be a gluon then? Maybe a gluon is there but it's not doing much. Perhaps eliminating gluons would allow quarks to flow in a current or at least be attracted to each other more freely making them more manipulate-able. I think this might have been done in a quark-gluon plasma http://en.wikipedia....rk-gluon_plasma

 

where the gluons are not confining the quarks due to the high energy level, similar to how electrons aren't confined in a normal plasma because of the high energy but if there was some kind of magnetic field with quarks, you could probably get the quarks to follow a path like a magnet with normal plasma.

 

It seems like the property of charge attraction and repulsion is the same for particles smaller and smaller in the atomic realm, and the only thing that seems to change is the amount of charges, so with that in mind it might be possible.

Edited September 16, 2011 by questionposter

[Schrödinger's hat]

Wait, why does there even need to be gluons for single protons if the quarks respond to each other's color charge attractively and always have attractive charges? I guess two are down and one is up, but its still a lets say Xcharge and Ycharge and Zcharge which are all attracted to each other, so why does there need to be a gluon then? Maybe a gluon is there but it's not doing much.

I think -- and I'm getting way out of my depth here, take this with a grain of salt -- that the gluons are the virtual particles that hold the protons and neutrons together.

The only way the quarks can attract each other and stay in a proton is by exchanging gluons, much like virtual photons are exchanged to keep electrons in their orbitals.

Perhaps eliminating gluons would allow quarks to flow in a current or at least be attracted to each other more freely making them more manipulate-able. I think this might have been done in a quark-gluon plasma http://en.wikipedia....rk-gluon_plasma

 

where the gluons are not confining the quarks due to the high energy level, similar to how electrons aren't confined in a normal plasma because of the high energy but if there was some kind of magnetic field with quarks, you could probably get the quarks to follow a path like a magnet with normal plasma.

This seems more like a situation in which color conduction would be a thing.

If the quarks are un-bound then they could carry color around much like a regular plasma can carry charge.

I'm still not sure how you would go about inducing a color-current, as the range of the strong force would mean the thing you're exciting it with would have to be inside the QGP.

Maybe you could excite it using the charge that the quarks also carry and an EM field? Maybe you could set up some situation in which the different color quarks have different potentials? Or use some kind of resonance/inertial effect if they have different masses...I don't know that color changes the mass.

I'm not even sure the idea of these forces/charges being separate things makes sense at the energies required for QGP.

[Shima]

 

 

... as far as I knew gluons could only act over tiny distances, and non-white collections of quarks aren't stable.

 

 

I guess that the quark matter is wholly color singlet and so stable, since the original baryon matter which converted to quark matter is colorless.

 

But since a cooper pair of two quarks has a net color charge, some stability conditions must be imposed in a color superconducting phase.

 

This is usually done by means of color chemical potentials (as the Lagrange multipliers), and as a result this phase is color singlet also.

 

I don't know whether we need a long range interaction to have some kind of conductivity or a short one.

 

To have a flow of charged particles (no matter what kind of charge we mean) the system must be in the weak interaction region.

In the case of dense baryon matter where the nucleons overlap, the strong interaction is so weak that the quarks can flow freely,

or jump from a nucleon to its neighboring nucleon. This may mean the color current.

 

 

 

...

 

I'm still not sure how you would go about inducing a color-current, as the range of the strong force would mean the thing you're exciting it with would have to be inside the QGP.

 

 

 

I think you want to remind us that the color force is short range and this is the reason why we can not excite the color conductivity with external tools.

 

I agree with you, but I can make an analogy of the Ohm's law (( E=\sigma J, \sigma is the conductivity)) for the quark matter.

 

To excite a color current we must impose an external Chromo-Electric field.

 

But the main question left : What is this kind of gauge Variant electric field ? Is it measurable? How can we made it?

[Shima]

 

 

I think you want to remind us that the color force is short range and this is the reason why we can not excite the color conductivity with external tools.

 

I agree with you, but I can make an analogy of the Ohm's law (( E=\sigma J, \sigma is the conductivity)) for the quark matter.

 

To excite a color current we must impose an external Chromo-Electric field.

 

But the main question left : What is this kind of gauge Variant electric field ? Is it measurable? How can we made it?

 

 

Sorry I had a typo : E= J / sigma is true.

[Schrödinger's hat]

To excite a color current we must impose an external Chromo-Electric field.

 

But the main question left : What is this kind of gauge Variant electric field ? Is it measurable? How can we made it?

As I said, I'm WAAAAY out of my depth here, I could entirely be talking out of my posterior.

The only thing I can think of is somehow having another property (regular charge, spin, mass etc) which varies in some way which is systematically linked to the color of the particles.

I am given to understand that quarks/gluons have spin. Maybe there'd be something systematic about the way the colors of the quarks in some protons/neutrons are arranged. If one were to align them all in a magnetic field before making our super-dense matter, could a further EM field then have some effect?

 

The one other thing is if there's something that goes whacky with the symmetries at very high energy levels, and you get some coupling to other types of field. How you'd have anything resembling what we think of as a machine or a device operating at such energies I have no idea.

 

At this stage I think I might just give up and wait until I've learned some QCD before attempting to think about this again :/ Have fun!

[Shima]

 

At this stage I think I might just give up and wait until I've learned some QCD before attempting to think about this again :/ Have fun!

 

Thank you a lot for sharing your thoughts

[questionposter]

So I have a question... So there's 3 different charges of quarks, does that mean there's 3 different gauge bosons to carry those charges or they all emit the same one? In either case, how does the 3 different types of gauge bosons add up to make one type of attractive force (proton's charge) in what way, or if they emit the same one, why are there different charges?

[Shima]

So I have a question... So there's 3 different charges of quarks, does that mean there's 3 different gauge bosons to carry those charges or they all emit the same one? In either case, how does the 3 different types of gauge bosons add up to make one type of attractive force (proton's charge) in what way, or if they emit the same one, why are there different charges?

 

 

 

There are 8 gluons which carry color and anti-color charges as the exchange particles for the strong forces.

You can find some details here:

 

http://en.wikipedia.org/wiki/Gluon

[questionposter]

There are 8 gluons which carry color and anti-color charges as the exchange particles for the strong forces.

You can find some details here:

 

http://en.wikipedia.org/wiki/Gluon

 

Well, ok, but how does that make a proton charge? How do those emit something that I say is a "positive" charge as opposed to a "red" charge?

Edited September 21, 2011 by questionposter

[Shima]

Well, ok, but how does that make a proton charge? How do those emit something that I say is a "positive" charge as opposed to a "red" charge?

 

 

The color charges and the electric ones are corresponding to two different spaces. The former is according to

the interaction of quarks and gluons and the latter is due to the interaction of quarks and photon.

Although we don't usually consider the electric interactions in the QCD lagrangian because the electromagnetic force is not strong,

quarks carry both charges which are relating to two different symmetry groups:

 

U(1)_{electromagnetism} and SU(3)_{color} both are local symmetries.

 

A proton consists of two valence Up quarks (everyone with +2/3 electric charge) and one valence Down quark (with -1/3 electric charge).

 

You can see that the proton charge is equal to +1.