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10

So there's this funny rule whose provenance I can't recall, but whose essence is: everything that is not forbidden, eventually happens. This rule is particularly fecund in quantum mechanics. If the process you describe is allowed, then every neutron already is a superposition of neutron and antineutron, and the question is just whether the oscillations ...


0

I think the above picture with captioning below answers the question best, at least for me. Basically the green quark emits a green-antiblue gluon, turning it blue. This gluon is absorbed by the blue gluon, and it changes from blue to green, restoring the color symmetry and keeping the Baryon overall colorless. And it happens so fast that no overall Baryon ...


0

No, not at all! The color of the quarks has no effect whatsoever. If you're studied intro physics, you know that a potential $V(x)$ is identical in every way to a potential $V(x) + V_0$ for some constant $V_0$. Now consider two hydrogen atoms, where I've set the potential at infinity to be $3 \text{ V}$ for one of them and $4 \text{ V}$ for the other. ...


0

Hadrons come in 2 families: baryons and mesons. Both of them consist from colourless combinations of quarks. Mesons contain pairs of quarks of colour-anticolour and hadrons contain 3 quarks of different colours making them white in analogy with regular colour perception. You are right that quark can change its colour by interaction with gluons, but the ...


3

If you take an electron and a proton there is a strong electromagnetic force between them because the electron has a charge of $-e$ and the proton has a charge of $+e$. However suppose you combine the electron and proton into a hydrogen atom. The hydrogen atom has a net charge of zero so there is no strong electromagnetic force between two hydrogen atoms. ...


1

This is related to the so-called "colour charge" carried by particles involved in strong interaction. Although at first it was proposed to allow same quarks exist inside the baryons (despite Pauli exclusion principle), it is also used to describe the ability of hadrons to be free of confinement — only colourless particles (or white) can be free. This is not ...


2

It is not true that scale invariance requires strong interactions. After all, free scalar field theory is scale invariant (and so is classical electromagnetism). In high energy interactions approximate scale invariance emerges because asymptotic freedom implies that free field theory is indeed a useful starting point. QCD is subtle because we cannot study ...


0

That is a good question but hard to answer. So far experimental particle physics is concerned, no signature of quark substructure observed till date. Nevertheless imagination of a theorist goes far beyond. There are few proposal already in the literature notably the idea of Preons. Which was considered as the constituent particles of quarks. But its a ...


-1

Think of the QCD vacuum inside the hadron as similar to a material with a dielectric constant. The electric field, here a QCD color charge field, as $\vec D = \vec E + 4\pi \vec P$. The self interaction of the gluons is similar to the polarization of a medium in classical electrodynamics. The chromo-electric displacement is then $\vec D = \epsilon\vec E$. ...


8

Symmetry and statistics. The quarks being fermions dictate a fully antisymmetric wavefunction of the three constituents of the baryon. The color wavefunction is antisymmetric, so the combined spin&flavor wavefunction must be symmetric. The spin 1/2 combination (SU(3) octet) is of mixed symmetry and so is the flavor symmetry of the baryon octet you ...


7

First, the neutron $n$ and the proton $p$ don't have "excited counterparts" in the decuplet, either, do they? Now, the two multiplets are completely different. One has eight $SU(3)_{\rm flavor}$ components, the other has ten. So it's clearly invalid to call one group "excitations" of the other. Because the quark content (charge and strangeness) is the ...


5

We usually do not talk about a "color electric field" to begin with. The strong force is treated fully relativistically from its beginning. If you want, you can define a "color electric field" and "color magnetic field" from the strong field strength tensor $G_{\mu\nu}^a$ in exact analogy to electromagnetism as $E^a_i := G_{0 i}^a$ and $B^a_i := \epsilon_{...


0

If you take some quark flavors to have color charge, $\psi_f\to U\psi_f$ with $U\in SU(3)$, and some others to have anti-charge, $\psi_g\to U^*\psi_g$, then the lagrangian $$ {\cal L}=\sum_{h=f,g} \bar\psi_h i\gamma^\mu D_\mu \psi_h $$ will not be gauge invariant, because $D\to UDU^\dagger$. In other words, this theory violates conservation of color.


2

(Do quarks have) color charges because of something? Boris Struminsky is though to be one of the first to postulate an additional quantum number for quarks, allowing for the $\Omega^-$ hyperion (comprising three strange quarks) to exist without violating the Pauli exclusion principle. Color charge was, hence, introduced as solution to this problem. ...


0

To perhaps give an answer in a slightly different way, it's complicated. One must keep in mind that the decomposition of the angular momentum into spin and orbital components is model dependent. In the language of the renormalization group, it is scheme and scale dependent. If you probe a hadronic system at a given length scale (or, equivalently, energy) ...



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