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78 votes

Why are all quarks and leptons of this universe the same?

Fairy Physics It is entirely possible to construct a theory of the universe which states: "All effects are caused by fairies. Each effect has its own fairy, and every fairy is unique. When two ...
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55 votes

Why the charge of the proton does not transfer to the neutron in the nuclei?

A proton can exchange charge with the neutron via a process called "pion exchange". In this process, the proton with quark content $uud$ sends a positive pion $u\bar{d}$ over to the neutron $...
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50 votes

Why the charge of the proton does not transfer to the neutron in the nuclei?

If I put a red billiard ball and a blue billiard ball in a bag, leave them for a while, and then draw one out, I will find I am holding a red ball or a blue ball. Never a purple ball. At the level of ...
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43 votes
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What is the experimental evidence that the nucleons are made up of three quarks?

What is the experimental evidence that the nucleons are made up of three quarks? Some strong pieces of evidence for the quark model of the proton and the neutron, not stated in another answer, are ...
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39 votes
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Proton: 2 up, 1 down quark, Neutron: 2 down, 1 up, how can Neutron: proton + electron?

A neutron is not "a proton and an electron". A neutron is not composed of a proton and an electron inside of the neutron. In quantum mechanics, particles can appear and disappear or change into other ...
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35 votes
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How (or when) do gluons change the color of a quark?

The idea that baryons contain three quarks is a significant oversimplification wrong. It works for some purposes, but in this case it causes way more confusion than it's worth. So you should stop ...
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34 votes

What is the experimental evidence that the nucleons are made up of three quarks?

Note that the original SU(3) quark model was entirely mathematical (The Eightfold Way) and was a brilliant way to explain the observed spectra of baryons and meson. The whimsically named quarks were ...
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  • 23k
29 votes
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Do the quark types differ from each other in ways other than charge and mass?

Yep, quarks of different flavours exhibit important differences in their properties. As we know, quarks participate to all known interactions – but the details of how this happens matter. Let's start ...
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27 votes
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Quarks in a hadron: where does the mass come from?

You say: Now, when we talk about energetically favourably bound systems, they have a total mass-energy less than the sum of the mass-energies of the constituent entities. and this is perfectly ...
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26 votes

Why doesn't the color force between two quarks have an inverse square law?

This is covered by a few existing answers (see for example About free quarks and confinement) though surprisingly it doesn't appear that anyone has asked this exact question before. Anyhow, the ...
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26 votes
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Why is the charmed eta meson its own antiparticle, but the neutral kaon is not?

Mesons are not elementary, they are composed of quarks. So take a look at their quark content. The charmed eta meson consists of a charm and an anti-charm quark, denoted $c\overline{c}$. An anti ...
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25 votes

Do quarks violate quantization of charge?

Quarks do not violate quantization of charge, it's simply that $\frac{1}{3}e$ instead of the electron charge $e$ is the smallest unit of electric charge.
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22 votes
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Are there any Baryons that have quark-antiquark combinations?

No, a three-quark baryon can not be be made out of two quarks and one anti-quark (and vice versa) as this would necessarily give the particle color. Each quark carries one of three colors (red, blue, ...
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  • 346
22 votes

Why are all quarks and leptons of this universe the same?

We know that the spectral lines in the spectrum of a binary star shift one way and then the other and this is correlated with its position in its orbit around its companion. Clearly, the constituents ...
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21 votes

Proton: 2 up, 1 down quark, Neutron: 2 down, 1 up, how can Neutron: proton + electron?

A neutron isn't a proton and an electron. The reaction involved in beta decay is $$n \to p + e^- + \bar{\nu}_e$$ where $\bar{\nu}_e$ is an electron anti-neutrino. But even that doesn't mean a ...
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21 votes

Is a 6-quark particle viable?

The deuteron (or $^{2}$H nucleus) is a color-neutral bound state of three $u$ quarks and three $d$ quarks. Because six quarks can combine to make a color-neutral state, this six-quark state is ...
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20 votes
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In which experiment did protons seem to consist of infinite amount of quarks?

Thanks for finding this amazing historical video. He's talking about the deep inelastic scattering electron proton experiment at SLAC. This showed evidence that high energy electrons scattered off ...
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20 votes
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Why the charge of the proton does not transfer to the neutron in the nuclei?

Good question! First, the motion of charge between macroscopic objects is defined by classical physics, specifically classical electrodynamics or classical Maxwell's equations to be specific. Nature ...
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  • 24.8k
20 votes

Do the quark types differ from each other in ways other than charge and mass?

If the six flavors ($d,u,s,c,b,t$) all had the same mass and charge, they'd all still be distinguishable in the sense that the model still includes observables that (if measured) would detect one ...
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19 votes

Are there any Baryons that have quark-antiquark combinations?

Pentaquarks contain three quarks and a quark-antiquark pair, and they are baryons, since baryons are defined as having an odd number of valence quarks.
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18 votes
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Is color charge a quantum mechanical observable?

Color charge in the sense of "being blue, red, green" is not a quantum mechanical observable because the $\mathrm{SU}(3)$ gauge transformations mix the colors. This means it is meaningless to say "We ...
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  • 105k
18 votes

Is a 6-quark particle viable?

In principle, a hadron with any number of quarks can be formed provided that the overall color is neutral. However, hadrons with more than three quarks (observed in particle accelerators) are unstable$...
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  • 24.8k
16 votes

Is there a quark conservation law?

Yes, there are the quantum numbers Charm, Strangeness, Topness and Bottomness, which are conserved by strong and electromagnetic interactions, but not by weak interactions. Upness and Downness are ...
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16 votes
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$SU(3)_F$ flavour symmetry and $SU(2)$ isospin symmetry

Both SU(3) flavor and SU(2) isospin are approximate symmetries of the Standard Model at low energies. Consider physics below the proton mass, where we can talk about the pions and kaons that are the ...
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16 votes
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Can muons decay into quarks?

No, muons can't decay into quarks because quarks are confined; the final product cannot be quarks, but rather composite particles made of quarks, such as mesons and baryons. The lightest mesons are ...
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16 votes
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Why is the mass of the proton such a precise value?

You say: a zillion gluons and quarks and anti-quarks self annihilating and popping into existence and while this is a very common way to describe the interior of a hadron like a proton it is ...
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15 votes
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What are Quarks made of and will they ever decay to this?

Quarks as we know them are fundamental particles, which means that they do not have smaller constituents. This however does not imply that they cannot decay. A particle in quantum field theory does ...
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15 votes

How (or when) do gluons change the color of a quark?

The model you are thinking about is really rudimentary and cannot explain the dynamics of Quantum ChromoDynamics, QCD . In this link there is a better exposition of what a proton is, within QCD. ...
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14 votes
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How can $\Lambda^0$ and $\Sigma^0$ both have $uds$ quark content?

The isospin is different. $I=0$ for the $\Lambda^0$ and $I=1$ for the $\Sigma^{0}$. This makes the $\Lambda^0$ an isospin singlet state but the $\Sigma^0$ is part of an isospin triplet. There are ...
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