I Quark Numbers in Quarks-Gluons Plasma: Avogadro's Number

[doubter]

TL;DR Summary

Why quarks numbers of the three colors where exactly equal in the initial quarks-gluons plasma?

Why quarks numbers of the three colors where exactly equal in the initial quarks-gluons plasma? Seeing the Avogadro number, even a 10E-20 additional excess in one color should give a lot of free quark tracks in bubble chamber.

 

[malawi_glenn]

TL;DR Summary: Why quarks numbers of the three colors where exactly equal in the initial quarks-gluons plasma?

Why quarks numbers of the three colors where exactly equal in the initial quarks-gluons plasma? Seeing the Avogadro number, even a 10E-20 additional excess in one color should give a lot of free quark tracks in bubble chamber.

Source?

 

[ohwilleke]

They don't have to be and we don't know that this is exactly true.

But, if the probability of each color is 1/3 (which is what happens when quark antiquark pairs are created, we don't really know how baryogenesis happened) and you have roughly 10⁸⁰ quarks in the universe, which are initially quark-gluon plasma, the law of averages is going to keep the proportions very close to equal.

Also, as a function of confinement, if you start from any kind of hadron, it will be color charge neutral, so heating those hadrons to a QGC will produce a net color charge neutral QGC at a very fine grained level.

It is also worth noting that while we can say with certainty that there are three distinct quark color charges (and three parallel antiquark color charges) in QCD, there is no observational test that can tell you which color any particular quark is. You can tell if it is a quark or an antiquark, but not which particular color a quark or an antiquark is.

 

[Vanadium 50]

Why quarks numbers of the three colors where exactly equal in the initial quarks-gluons plasma?

Why does every north magnetic pole have a corresponding south magnetic pole?

 

[doubter]

It is in the Maxwell's equations, where is the equation governing the fact that the initial post big-bang quark-gluon plasma was perfectly "white"?

 

[mathman]

Physics before big bang is a big unknown. There may be underlying physics forcing exact equality.

 

[Vanadium 50]

It is in the Maxwell's equations, where is the equation governing the fact that the initial post big-bang quark-gluon plasma was perfectly "white"?

Are you asking us or telling us? And what does Maxwell have to do with it?

 

[doubter]

Maxwell's equation is just the answer to your question: "Why does every north magnetic pole have a corresponding south magnetic pole?" And I am looking if there is a similar argument explaining the "white color" of the initial quark-gluon plasma.
Quarks introduction explains what is observed in high energy accelerator experiments, but at the cost of introducing new freedom degree of parameters, such as the initial equality of the quark number of different colors.
I am just worried to know it there are theoretical arguments explaining this fact?
It is even more strange that in the big bang it is assumed that the energy was transformed in quark-antiquark pairs and that afterwards a mechanism broke the baryon number leading to a small excess of quarks, but without giving a small excess in one color.

 

[Vanadium 50]

Maxwell's equation is just the answer to your question: "Why does every north magnetic pole have a corresponding south magnetic pole?"

So why do you accept this for magnetc charge and not for color charge?

 

[vanhees71]

The difference in between "magnetic charge" in electrodynamics and "color charge" in QCD is that the former simply is 0, and that's why the multipole expansion of magnetic fields starts with the dipole term, i.e., there is simply no magnetic charge (usually called "magnetic monopoles") in elecctrodynamics.

In QCD you have from a naive, supericial point of view two sorts of color-charged elementary objects (i.e., fields entering the Lagrangian), i.e., the quarks, coming in three colors and the anti-quarks coming with the corresponding anti-colors. Technically speaking the color group is realized on the quarks by the fundamental representation of SU(2) and on the ant-quarks by its conjugate complex one. Then there are the gluons, on which the color SU(3) acts in the adjoint representation.

Now it is very likely that there is confinement, i.e., that the gauge invariance of all observables is guaranteed by the fact that we can only observe color-neutral objects, i.e., most obviously the usual hadrons (baryons, color-neutral bound states of three quarks, anti-baryons, color-neutral bound states of three anti-quarks, and mesons, color-neutral bound quark-anti-quark states).

 

[doubter]

To Vanadium 50: it is not a question of accepting or not a theory, it is a question of trying to have a "complete" theory, i.e. which answers more questions than it creates new ones. Quark theory answers many high energy accelerator experiments, but what about the universe history? or about the observation of "natural" process, i.e. in astronomy, in cosmology.

Physicists changed the paradigms, in early twenty twenties centuries, physicists developed theories to explain "natural" events, i.e. photoelectric effect, absorption and emission rays, Michelson-Morley experiments, stable atoms although it was in contradiction with bremsstrahlung radiation predicted by Maxwell's equations, Electron scattering, etc...

Relativity, Quantum Mechanics, QED, was developed and explained these observations.

Afterwards, physics, in an attempt to unify all interactions, develops theory to explain what is observed at "ultra" high energy experiments, i.e. in accelerator, at energy so high that it does not naturally append any more in the universe, even in astronomy.

To vanhees71: I do not understand why we could not observe "colored particles", let's imagine that there was a small excess of "rod" quarks in the baryogenesis epoch, then after quark decay it should survive only "red" free up quarks that can catch electrons to make "upelectronium" atom, i.e. a hydrogen-like atom in which a electron is bind to a "red" up quark.

Are we able to check in stellar absorption rays that there are no faint rays with energies about -(2/3)**2 13.6 eV/n**2 ? (about, not equal, because the up quark mass is not so high than the proton one)

Indeed, if there was a "red" color excess in the initial epoch, it is not possible for the excess "red" quarks to form baryons with other "green" and "blue" quarks, and thus they should remains free, i.e. no making "composite" particles, and thus should catch electrons in the nucleosynthesis epoch.

PS: I forgot to thank you for replying to me

 

[Vanadium 50]

The difference

We choose our E&M equations so as not to get monopoles. We could do the same thing in QCD with exposed color, (not allowing it) and maybe we already have.

In both cases you have an observational fact that we don't see free color/monopoles, and in both cases if there were such things in the early universe they wou;d have been inflated away.

If the OP isn't happy drawing this parallel, he needs to explain what "rules" he's using - otherwise this is just "if things were different theyt's be different". Which is true, but not helpful.

Put more succinctly, what's the difference between a universe without free color charges and one wiih one free charghe a quadrillion light years away?

 

[doubter]

It is not exactly a parallel: div(B)=0, as chosen (I agree), tell us that there is no magnetic monopole and that only dipole exists.

The quark theory postulates that three quark colors exist, and that in the initial quark gluon plasma, the quarks were free, thus not to be associated in "white" composition.

But I should very happy to see the equation, or mechanism, involving their equality number in this plasma.

About the Universe, beside what we observe in our laboratory, what are the observations requiring the existence of quarks?

 

[malawi_glenn]

tell us that there is no magnetic monopole

Then why are scientists searching for magnetic monopoles?

Why quarks numbers of the three colors where exactly equal in the initial quarks-gluons plasma?

I still would like to have a reference for that statement.

 

[snorkack]

What is the mass of a free quark?
Should the mass of a free quark be the same no matter whether it is produced by the (forbidden) process of pulling a hadron apart, or (allowed) is primordial?

 

[vanhees71]

We choose our E&M equations so as not to get monopoles. We could do the same thing in QCD with exposed color, (not allowing it) and maybe we already have.

Color charge in QCD is analogous to electric charge in QED, not to magnetic charge, which indeed in QED is simply assumed to vanish.

In both cases you have an observational fact that we don't see free color/monopoles, and in both cases if there were such things in the early universe they wou;d have been inflated away.

The difference is that in QED charged particles/states are observable and definable as gauge-invariant quantities. In QCD it looks similar, but experience shows that there is "confinement", i.e., we only observe color-neutral (bound) states. The challenge is to understand this from first principles, which afaik is not yet achieved completely.

If the OP isn't happy drawing this parallel, he needs to explain what "rules" he's using - otherwise this is just "if things were different theyt's be different". Which is true, but not helpful.

Put more succinctly, what's the difference between a universe without free color charges and one wiih one free charghe a quadrillion light years away?

Indeed, that's among the challenges in understanding confinement, and you don't even need to consider the entire universe. Already in relativistic heavy-ion collisions and the formation of the quark-gluon plasma, it's a challenge to explain dynamically, how color-charge neutrality in the observable final state is reached. As I said already above, I don't think that this is already completely understood.

 

[snorkack]

What is the force holding a quark in hadrons? I´ve read estimates like 14 tons.

 

[vanhees71]

I don't think that the notion of "force" is a good picture. The picture is that when you try to separate color-charged objects like a quark and an anti-quark bound in a meson due to confinement you have to put in so much energy that more and more new quarks and antiquarks are formed, binding themselves again to hadrons ("string breaking", "fragmentation"), but also this is only a qualitative picture, which can be made quantitative only in a semi-empircal way by defining socalled "fragmentation functions". The trouble with the strong interaction is that it's strong at low energies, such that we cannot use perturbation theory in this realm. The only way to understand the low-energy sector of QCD from first principles is lattice QCD, i.e., the evaluation of observables like the hadron-mass spectrum by calculating the appropriate (gauge-invariant!) correlation functions of quark and gluon fields in a discrete space-time lattice.

 

[snorkack]

I don't think that the notion of "force" is a good picture. The picture is that when you try to separate color-charged objects like a quark and an anti-quark bound in a meson due to confinement you have to put in so much energy that more and more new quarks and antiquarks are formed, binding themselves again to hadrons ("string breaking", "fragmentation"),

Yes. Because there is the other end of the string, at an opposite colour.
What should happen if the string cannot break because there is no opposite colour end?
The tension of the string is 1,4*10⁵ N. One lightyear is 3*10⁸ m/s*3,15*10⁷s=9,4*10¹⁵ m. Which means a hadron 1 lightyear long should have energy of 1,4*10⁵*9,4*10¹⁵=1,3*10²¹ J. And rest mass of 13*10²⁰/9*10¹⁶=1,4*10⁴ kg, also equalling 14 tons.
Of course, the world is not 1 lightyear small, it is 14*10⁹ lightyears radius, so a free quark should have a mass of 200*10⁹ tons?

See, assuming that there are primordial free quarks gets into some paradoxes trying to figure out what their colour fields are like and what their rest mass is.
Do these paradoxes have any solutions besides the trivial one (that in addition to expressly forbidden formation of free colour, primordial existence of free colour is implicitly also forbidden)?

 

[doubter]

My concern is not about the confinement, but about the fact that if in the very early universe epoch the matter is created from pure energy by quark-antiquark pair generation, which resulted in a quark-gluon plasma due to the high temperature-density with a mechanism breaking the baryon number is anterior to the neutral baryons generation, so for me it is strange that quarks are produced in equal color quantities. So I agree with vanhees71 that something is not well understood.

But, I though that in quark-gluon plasma generation in collider, as we start with neutral colors baryon, and that the only way to produce more quarks is by quark-antiquark generations, it is natural that the global color remains neutral?

 

[malawi_glenn]

for me it is strange that quarks are produced in equal color quantities.

Can you (third time I ask) give a reference to this claim?

 

[doubter]

Hi Malawi_glenn
I have no reference for that, just the fact that if there was a very small excess of one color, for exemple red, in the very early universe epoch, then we should see free up quark tracks in our bubble chambers as these red quarks in excess would never been able to form neutral baryons

 

[snorkack]

Hi Malawi_glenn
I have no reference for that, just the fact that if there was a very small excess of one color, for exemple red, in the very early universe epoch, then we should see free up quark tracks in our bubble chambers as these red quarks in excess would never been able to form neutral baryons

That would depend on the details of the free colour fields.
Would a free red quark wander around as a low mass unbound object in our bubble chambers? Or would it be a massive object attracting white baryons both by intermediate level (coloured-white) strong force and by gravity, resulting in a red black hole? How are you going to tell apart a red primordial black hole from a white primordial black hole?

 

[doubter]

quarks are not massive at all, last models predict that the up quark mass is just about 4 fold that of the electrons, as its charge is 2/3, we just should see circular track similar to that of positron with a radius about 6 fold larger
the electron as being ponctuel (no experiment has never evidenced some electron radius), could also be considered as a black hole in your view, however accelerated electron emits Bremsstrahlung photons and also produced ionisations

 

[snorkack]

quarks are not massive at all, last models predict that the up quark mass is just about 4 fold that of the electrons,

Inside a white hadron.
See post 19 for one potential derivation of the mass of a free quark. Can you show what the real mass of a free quark is?
And of course it is not only free quarks and antiquarks that carry colour. Gluons also have colour. Which means that a primordial colour carrier might not be a (charged, impossible to neutralize) quark or antiquark, but instead a free gluon - uncharged...

 

[Drakkith]

My concern is not about the confinement, but about the fact that if in the very early universe epoch the matter is created from pure energy by quark-antiquark pair generation, which resulted in a quark-gluon plasma due to the high temperature-density with a mechanism breaking the baryon number is anterior to the neutral baryons generation, so for me it is strange that quarks are produced in equal color quantities. So I agree with vanhees71 that something is not well understood.

A similar issue occurs in matter-antimatter asymmetry, just in the opposite direction, in that it is not known why matter vastly outnumbers antimatter. Some things just aren't known.

 

[snorkack]

A similar issue occurs in matter-antimatter asymmetry, just in the opposite direction, in that it is not known why matter vastly outnumbers antimatter. Some things just aren't known.

Yes. But now the question is as follows:
if the universe somehow ended up with a primordial net baryon charge (obvious observable fact), why assume that universe does not also have a modest primordial net colour charge?
If it were true, what would the effects be? How would the primordial colour carriers interact with ordinary white matter through coloured-white strong force? Through gravity? Would they be something conspicuous and distinctive? Or something conspicuous but indistinct? Like a red black hole which looks nearly the same as a white black hole?

 

[doubter]

colored gluons are also ruled by confinement, and just uncolored gluons can be free
I guest that residual colored quarks should catch an electron to form an exotic atom
And again I do not see why they should be considered as black hole

 

[snorkack]

colored gluons are also ruled by confinement, and just uncolored gluons can be free
I guest that residual colored quarks should catch an electron to form an exotic atom

Only if they are positively charged (+2/3 quark or +1/3 antiquark). Negative residual quarks (-1/3 quark or -2/3 antiquark) will not be electrostatically attracted to electrons. Neither will neutral residual coloured gluons.

And again I do not see why they should be considered as black hole

To begin with, if nothing can get out of a black hole then neither can quarks.
Electric charge is a hair a black hole can have. If charged particles fall in a black hole, it becomes a Reissner or Newman, charged black hole.
Since colour field, like electrostatic field, stretches to infinity, when a residual coloured quark or gluon falls in a black hole, the black hole should acquire the colour.

 

[weirdoguy]

pure energy

There is no such thing, just like there is no "pure velocity", etc. Energy is a property of things, not thing itself.

 

[Vanadium 50]

I thought we were making progress in what exactly the question is, but I am not so sure.

1. As mentioned, there is no such thing as "pure energy"
2, If I pop a red quark out of the vacuum, I necessarily have to also pop an anti-red antiquark out of the vacuum.
3. All quarkls of the same flavor have the same mass, irresepective of color. Indeed, we have complete freedom to define what we call what color - what @vanhees71 calls "red" I can call "green" and every observable will be exactly the same. (That's what the symmetry means)
4. There is no such thing as an uncolored gluon.

This has to be our starting point. If you don't accept this, we need to get this cleared up before moving on.