Questions tagged [confinement]

Color confinement is the concept that particles that possess color charges (quarks and glouns) can not be found freely, and only color-free combinations can be observed.

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134 views

Do hadrons have color moments?

Hadrons have electrical moments since they are made up of both positive and negative charges. Water molecules have dipole moments for the same reason even though they are electrically neutral. Since ...
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Why are there no composite particles with fractional charges?

Mesons are composed of a quark and an anti-quark, so no fractional charge is possible mathematically. Baryons are composed of three quarks, no anti-quarks mixed in with quarks, so no fractional charge ...
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About the validity of the dilute gas approximation

In the compact QED (cQED) in $(2 + 1)$ dimensions confinement /deconfinement property is described in terms of boundness of monopole-antimonopole pairs (Berezinskii-Kosterlitz-Thouless phase ...
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Can mesons be in $b \overline{b}$, $r \overline{r}$, $g \overline{g}$ states?

Can a meson be in a pure $b \overline{b}$, $r \overline{r}$, $g \overline{g}$ state or does it have to be in the $\frac{1}{\sqrt{3}}\left(b \overline{b}+r \overline{r}+g \overline{g}\right)$ state? ...
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How can we split a proton? [closed]

I have heard the following statements: Quarks always exist in a group of 2 or 3, and can not stand alone. Protons are made up of 2 up quarks, and 1 down quark. Quantum mechanics allows us to entangle ...
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How does the mere movement of gluons keep quarks together?

You know the strong force (the one that keeps quarks together). Well it works by exchanging gluons right? So how does that force keep the quarks together? I mean you can imagine that process as three ...
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What happens when one separates a quark-antiquark pair?

in particular, if the distance is more than about 1 fm?
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In a Big Rip scenario, would color confinement cause a singularity to form?

The energy in a gluon tube between quarks increases approximately linearly with the distance between them, and when that energy is sufficient to spawn a quark-antiquark pair out of the vacuum, it does ...
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QCD energy scale $\Lambda_{\rm MS} $, $\Lambda_{\rm QCD}$, …?

Why there seems to be different conventions of QCD energy scales? Is that due to the running coupling? For example in Wikipedia https://en.wikipedia.org/wiki/Coupling_constant#QCD_scale: $$ \Lambda_{\...
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Why quarks are confined? Why can't they be found in unbound states?

No one has observed before a "free" quark, i.e. a quark in an unbound state. According to one paper, I read that $p\bar{p}$ collision produce unbound $t\bar{t}$ pair which quickly decay into ...
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Can a baryon consist of two quarks and an antiquark? Or a pentaquark be made of three quarks and two antiquarks? [duplicate]

I suspect these particles exist, but are extremely short-lived, even compared to other unstable, exotic particles...
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Validity of Seiberg-Witten theory and the understanding of notion “Effective field theory”

I am reading "An Introduction to the Confinement Problem" book by Jeff Greensite https://books.google.ru/books?id=atwRBwAAQBAJ&printsec=frontcover&hl=ru#v=onepage&q&f=false, ...
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Can a gauge theory with $SU(2)_{left}*SU(2)_{additional}$ symmetry contain confinement?

Consider a gauge theory with $SU(2)_{left}*SU(2)_{additional}$ symmetry. By $additional$, I mean adding a new symmetry between an electron and a quark(like up quark and electron forming a doublet). ...
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Permitted bound states in extended QCD color group $SU(4)$

I'm very much curious about the possible quark combinations to form bound states in $SU(4)$ QCD. We already know Wilson has proven that only colorless combinations can arise in $SU(3)$ of these ...
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Abelian theory with confiment in 4d (Polyakov book)

In chapter 4.3 of Gauge Fields and Strings Polyakov study effect of monopoles. He make few statements: In 4d Maxwell theory with monopoles, exist phase transition, if $e_0^2> e_c^2$ it is ...
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At the Big Bang, when particles were created, could free standing quarks (not bound in a hadron) have been created and remain alone today?

You can't pull a quark out of a hadron, but at time $T = 10^{-43}$ seconds or shortly thereafter, when all particles were created, wouldn't all quarks be individual, and not grouped into hadrons, (...
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Phase transition in 3+1 abelian theory

In historical paper A View From the Island, A. M. Polyakov wrote at 6th page: In the abelian case, these dislocations turned to be just the world lines of magnetic monopoles and I predicted the ...
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Models of confinement based on negative mass carriers

In the old Yukawa model of nuclear forces, it was proposed that short-range interactions were mediated by exchanges using massive force carriers (originally, mesons were proposed for this). If one ...
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Simple “toy-model”-like explanation of quark confinement (QCD) and accompanying math

I have a qualitative understanding of quantum chromodynamics within nucleons and between nucleons, but I do not understand the math behind some of the physics like quark confinement. What is the math ...
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Quark confinement mechanism

As far as I understood: Quark confinement states that observing individual quarks is not possible, color charged quarks are confined into hadrons. As we try to pull them apart, force between them ...
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Is it possible to derive a non-mass gap from the Yang-Mills action? [duplicate]

The action: $$J=∫Tr(F∧⋆F).$$ Is it possible to find the non-mass gap property from the Yang mills action? If so, how?
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What is quark 'confinement' in the context of Yang-Mills Theory?

In the context of Yang Mills Theory, what is quark confinement? Please try to explain as simple as possible (obviously without being too general)
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Why there is no such a thing as colour moment?

I was busy google about different types of electric and magnetic dipole moment then a thought suddenly striked me, why there is no colour multipole moment?
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Why hasn't Peter Higgs solved the Yang-Mills prize problem?

The Higgs mechanism gets rid of the mass gap problem, and it's been experimentally proven, so why is there still a problem? Why are the million dollars still up for grabs?
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Can particle with fractional charge exist in isolation?

Since quarks are ruled out I wonder if it is possible for free fractional charge to exist not counting virtual particles?
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What happens when somebody solved mass gap problem like ultraviolet catastrophe? [closed]

Just curious if somebody came along and proposed a good mathematical solution to the millennium problem but it is not intuitive at first, what happens then? this person can rigorously proof the ...
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How do you reconcile quark masses with notion of confinement?

In trying to understand exactly what confinement means, I have been reading 't Hooft s original paper on 2D QCD at large $N$. In the paper he shows that the quark propagator pole is moved to infinity, ...
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How can we tell a theory is confining?

Physically, I understand what it means for a theory to be confining. The elementary particles are not observable, but only composite particles are. The classic example is QCD, where quarks are ...
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Why do we still call the electron charge the elementary (EM) charge?

The electron is an elementary particle, part of the SM, pointlike, with no substructure, or spatial extent. Its intrinsic properties include its EM charge, which we still call the elementary charge. ...
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How are quarks assigned color charge?

As always, I'll preface that I am wildly undereducated, so i may be overlooking something or be completely unaware of another relevant property. Color Confinement dictates that to "assemble" a baryon ...
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Asymptotic freedom and momentum exchange

Why is the momentum exchange very high for low distances? For sufficiently short distances or large exchanges of momentum https://en.wikipedia.org/wiki/Asymptotic_freedom While I think about ...
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Why do mesons decay?

Why do mesons decay shortly while baryons are more stable? And why do mesons decay, meaning that there are unstable, while they formed because meson is more stable than the two corresponding quarks? ...
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If quarks don't exist individually how can we say baryons are made up of three quarks?

We know the composite subatomic particles are made up of odd number of quarks (at least 3 for baryons ) or combination of quarks and antiquarks (mesons). My question is if they don't exist ...
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Below which energy would the weak interaction become confining?

Claudson et al considered an alternative formulation of the standard model where the SU(2) interaction was strengthened to become confining below ≈ 300 GeV, above the electroweak scale. Consider if ...
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Would Color Confinement apply in higher dimensions?

As I understand it color confinement comes from the fact that as the distance between two color charges increases the color potential energy increases, instead of decreasing, and the energy needed to ...
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Why do we have 3 quantum colours?

I understand the need to invoke colour as another quantum state to explain the observation of uuu ddd and sss baryons. I just wanted to know if there was some other property which explains why we only ...
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Why does the divergence of a QFT's coupling constant under RG flow trivialize the theory if it occurs in the UV but not in the IR?

When you first learn quantum field theory, at some point you calculate the beta function (to leading order) for a renormalizable coupling constant of some theory like $\varphi^4$ theory, Yukawa theory,...
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Can a quark quantum tunnel outside a nucleus?

I read that a particle wavefunction can extend over a thin barrier and there is a probability of finding it over the barrier even though it doesn't have the necessary energy, what about quark?
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How and why is the pentaquark stable if it consists of 4 quarks and an antiquark?

If matter and antimatter annihilate each other, why is the pentaquark stable since quarks are matter and the antiquark is antimatter?
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Why are mesons only made of a quark-antiquark pair? [duplicate]

Why can't we have a meson made of two quarks, why does there have to be the antiquark too?
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1answer
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Clarification about confinement of colour charged objects

In lecture today we were reviewing the QCD lagrangian, and discussing hadronic wavefunctions. My lecturer said that QCD alone allows for states of colored hadrons, however because we do not see ...
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Spaghettification on quarks?

Imagine a nucleon falls into a black hole, I would expect the gravitational force acting on each quark to be drastically different but due colour confinement wouldn't there more pairs of quarks being ...
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Why is color confinement a difficult problem?

Assuming color force follows a constant rule of force instead of an inverse square rule of force. And that red, green and blue are all attracted to each other. Why is color confinement considered a ...
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What is the relation between the Gribov problem and color confinement?

I have heard that the Gribov problem is in some way related to color confinement (For instance: Gribov copies and confinement). Although I understand what both the Gribov and confinement problems are, ...
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How do we know that gluons travel at the speed of light?

Since gluons are located within nucleons and immediately outside of them, how do experiments determine parameters like their speed? Is it possible we could be assuming they travel at the speed of ...
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Four-fermion “contact” interactions differing from those arising from the Standard Model

In the 1998 article Compositeness Test at the FMC with Bhabha Scattering, it states that: It was pointed out that the existence of quark and lepton substructure will be signalled at energies well ...
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How to “build” a proton

Sabine Hossenfelder in her column The End of Theoretical Physics As We Know It made the following statement: For example, we have a perfectly fine theory that describes the elementary particles ...
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Can we find a free gluon?

I have read these questions: Quark intrinsic angular momentum and the Proton Spin Crisis About free quarks and confinement https://en.wikipedia.org/wiki/Gluon And it made me curious. I understand ...
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Difference between boundedness (electrons around nuclei) and color confinement (quarks)

I have read these questions: How does the orbiting of electrons around nuclei START? Bound electrons don't move, right? Do different orbitals overlap in multielectron atom? What is the difference ...
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How does it make sense to talk about, for instance, quarks traveling at near lightspeed while confined to a volume as small as a proton?

How does it make sense to talk about, for instance, quarks traveling at near lightspeed while confined to a volume as small as a proton? The distances are so small, and the speed so high, that the ...