The quark model postulates that the hadrons such as protons and neutrons have an inner structure; quarks.

learn more… | top users | synonyms (1)

3
votes
2answers
46 views

Do quark charges repel one another?

Positive electrical charges repel other positive charges, and negatives repel negatives. But does that happen for quarks, too? I never saw mention of it, but if so, that would mean the up quarks in a ...
-1
votes
0answers
25 views

Relationship between electrons (leptons) and quarks

I assert the following is true: Either: electrons are made up of (two) quarks Or: Quarks are made up of some kind of smaller particles, which also make up electrons. I think this must be the case ...
0
votes
1answer
61 views

Does gravity exist between quarks in a neutron?

Does gravity exist between quarks in a neutron? I mean, I've learned that gravity exists between objects that have mass/energy. But does this apply between quarks in a neutron?
-1
votes
0answers
14 views

Question about Bubble chamber reactions [on hold]

The bubble chamber pic of event which was exposed to a K- beam in a liquid hydrogen bubble chamber. So, the target consists of protons.
2
votes
2answers
20 views

Standard-model flavor symmetry

If we consider the chiral Lagrangian after the spontaneous symmetry breaking, we have got fermion masses and Yukawa couplings to the physical Higgs boson. So it follows global symmetries in flavor ...
3
votes
1answer
56 views

How to build tetra-quark mesons symmetry group?

I was thinking about the issue while reviewing my group theory notes. One can construct mesons with a nonet as an octet and a singlet, $SU(3)\otimes SU(3) = 8\oplus \bar{1}$. In a same way but for ...
0
votes
1answer
23 views

How would one go about drawing a Feynman diagram of color screening and anti-screening in QCD?

Title really explains this one. I'm not sure how to put together a diagram of the lowest order for colour screening and anti-screening in QCD. Seems to be a lack of diagrams for this in the ...
4
votes
2answers
201 views

Can quarks be considered real and elementary?

In our current theories all hadrons are made up of quarks and gluons. This view reduces considerably the big family of hadrons by providing a very logical structure in which all quantum properties ...
0
votes
1answer
40 views

Raising and lowering operators for a composite isospin $SU(2)$ system

Consider pion states composed of $q \bar q$ pairs where $q \in \left\{u,d \right\}$ transforms under an $SU(2)$ isospin flavour symmetry. These bound states transform in the tensor product $R_1 ...
1
vote
1answer
20 views

Why do certain mesons not self-destruct? [duplicate]

As I understand it, particles and antoparticles annihilate one another. But some mesons (and pions?) consist of a quark and its antiquark. How can they exist without the two particles annihilating ...
1
vote
0answers
25 views

Parts of the Quark Wavefunction

Quarks are fermions meaning that they have an antisymmetric wavefunction. Under particle exchange the sign of the wavefunction. The wavefunction is made up of a few different parts $$ \psi_{Total} = ...
7
votes
2answers
384 views

Quarks falling in a black hole?

All I know about quarks is that they make up protons and neutrons and you can't really pull a quark pair apart, you just end up with 2 quark pairs because of all the energy you added becomes 2 new ...
11
votes
1answer
538 views

Why is the charmed eta meson its own antiparticle, but the neutral kaon is not?

I have a limited understanding of antiparticles, so this may be why I am unable to explain why certain mesons are their own antiparticles, while others are not. My understanding is that antiparticles ...
-1
votes
1answer
33 views

Can a massless quark exist?

Is there any possible way to extract all the mass of a quark? Probably under extreme Gs or heat or pressure?
7
votes
2answers
100 views

How can $\Lambda^0$ and $\Sigma^0$ both have $uds$ quark content?

Title says it all: How can $\Lambda^0$ and $\Sigma^0$ both have $uds$ quark content? Doesn't this make them the same baryon?
0
votes
1answer
32 views

Gluon to quark scattering

I am trying to calculate the $g g\to q \bar q$ amplitude but am finding it intractably complex. I have determined that there are only two independent polarizations that contribute non-zero ...
8
votes
2answers
455 views

Possible implications of Tetraquark/Quark Quartet

Today on Nature's website appeared a news about the discovery of a quark quartet (formed from two quarks and two antiquarks). They say that this particle containing four quarks is confirmed. This is ...
3
votes
2answers
67 views

Are the properties assigned to quarks meaningful?

Suspect this may have been asked before, but can't find it. My question is: If you can never have a free quark, what sense does it make to attribute properties to them, since you can never ...
0
votes
1answer
111 views

Why are quarks fundamental particles? [closed]

A neutron decays into a proton by changing one of its down quark into an up quark and releasing energy, positron and neutrino particle. So, a down quark can decay into an up quark. If a quark ...
1
vote
0answers
69 views

On shell and off shell simultaneously?

I am considering the following one loop virtual correction in the DIS process: where I have a quark of momentum $p$ coming in, emitting a gluon before interacting with a photon of momentum $q$ to ...
4
votes
4answers
81 views

Is there a theory where there are (recursively) infinitely smaller particles?

So I read that electrons are just points, with no mass, and furthermore, protons look like they have some "size" but that's really 3 "point-like" quarks. We first thought atoms were the smallest ...
3
votes
1answer
76 views

How to calculate U-spin for baryons

I am trying to calculate U-spin for sigma baryons. I don't know why U-spin for $\Sigma^{+}$ and $\Sigma^{-}$ and $\Sigma^{*+}$ is 1/2, but for $\Sigma^{*-}$ is 3/2? I know that $\Sigma^{+}$ and ...
1
vote
0answers
20 views

Why are quarks and gluons confined [duplicate]

I understand that quarks and gluons are confined to the particle they are part of but why is this? It seems that the color force is the only force that causes confinement so what is different about ...
4
votes
2answers
217 views

Dirac magnetic monopoles and quark fractional electric charge quantization

When applying the Dirac quantization rule for electric and magnetic charge, I assume one is considering unit electric charges such as electrons. How does the Dirac quantization rule apply for the ...
1
vote
1answer
71 views

What is cause of quantization of charge? [duplicate]

What is cause of quantization of charge? When we rub two objects only an integral number of electrons or charges can be transferred is this the reason? Why electron has the smallest possible charge? ...
1
vote
3answers
78 views

What are the six quark mass values when extrapolated to Planck energy?

Let us assume that the standard model is correct up to Planck mass. (Yes, I know, this is a big assumption.) If we continue the running of quark masses with energy (due to renormalization), what are ...
0
votes
1answer
27 views

What maximum energy can be stored in a gluon field flux tube

Question is as clear as stated in title. What is the maximum energy that can be stored in a gluon field flux tube without production of an quark anti-quark pair? And how much it usually store in a ...
-1
votes
4answers
107 views

What is mass constituted by quarks in a proton?

In a question I read Quarks in a hadron- where does the mass come from "The sum of the masses of the quarks in a proton is approximately $30~\text{MeV}/c^2$, whereas the mass of a proton is ...
5
votes
2answers
803 views

Quarks in a hadron- where does the mass come from

We know that the sum of the masses of the quarks in a proton is approximately $9.4^{+1.9}_{-1.3}~\text{MeV}/c^2$, whereas the mass of a proton is $\approx931~\text{MeV}/c^2$. This extra mass is ...
5
votes
2answers
137 views

Fractionally charged Quarks

Just wondering what the evidence is for fractionally charged quarks, is it simply enough to say that as we see deep inelastic scattering of electrons (at high energies) off the nucleus of an atom ...
1
vote
1answer
80 views

Collision symmetry and measuring the asymmetry in the Drell-Yan process

I saw a talk the other day about an asymmetry in the Drell-Yan process caused by CP-violation: Apparently one way this can be measured (ATLAS is doing this) is to collide protons and observe the ...
5
votes
2answers
98 views

What evidence is there of the existence of quarks?

What is the experimental evidence that suggests the existence of quarks? How were they discovered? I'm going to assume a particle collider is involved, as it tends to be the case with most subatomic ...
1
vote
0answers
44 views

Coulombs Law on Quarks [closed]

As from opinion from others the question don't seem to be clear so I did some changes. What is 5.33... it is 5+0.3+0.03+0.003+.... this sequence does not ends. now if we have a ball and we need to ...
0
votes
1answer
62 views

When were quarks discovered?

I know this sounds stupid. Especially to those of you who are actual physicists. I am a 7th grade above-level student who knows a little bit more that the basics of physics. I have recently discovered ...
32
votes
4answers
13k views

Why do electron and proton have the same but opposite electric charge?

What is the explanation between equality of proton and electron charges (up to a sign)? This is connected to the gauge invariance and renormalization of charge is connected to the renormalization of ...
3
votes
1answer
51 views

Why is the top quark mass reconstructed too high when the bottom quarks were swapped (semileptonic decay of a ttbar pair)?

I use a dataset containing simulated events of semileptonic $t\bar{t}$ decays ($t\bar{t} \rightarrow W⁺b W⁻ \bar{b} \rightarrow q\bar{q}bl\nu_l\bar{b}$) at CMS, LHC. For each event, the four-momenta ...
4
votes
0answers
36 views

Doubts about quark confinement, the pole mass and the quark gluon plasma

I have seen written a few times that the notion of a pole mass for a quark contradicts the quark confinement picture and that non-perturbatively it is expected that the quark pole mass be infinite. ...
1
vote
1answer
38 views

Is it possible to create a quark-gluonic reactor to produce energy with help of strong interaction?

Is it possible to create a quark-gluonic reactor to produce energy with help of strong interaction? Can it be done with quark-gluon plasma?
7
votes
2answers
629 views

How quark electric charge directly have been measured?

How quarks electric charge directly have been measured when quarks never directly observed in isolation? (Due to a phenomenon known as color confinement.)
7
votes
3answers
2k views

How do I know the proton isn't made of 3 anti-down quarks?

I have a proton, how do I know that it is made of 2 up quarks and 1 down quark or if it is made of 3 anti-down quarks, each with different color charges? This question is also applicable to the ...
3
votes
2answers
115 views

Quark composition of the neutral pion

I wonder why the neutral pi meson is $$ | \pi^0\rangle = \frac{1}{\sqrt{2}}\left(\vert u\overline {u}\rangle - \vert d \overline{d} \rangle \right) $$ and not $$ | \pi^0\rangle = ...
0
votes
0answers
29 views

Ratio of decays rates for $\rho \to \pi + \gamma$ and $\omega \to \pi + \gamma$

How easily are the ratio of decays rates for $\rho \rightarrow \pi + \gamma$ and $\omega \rightarrow \pi + \gamma$ obtained? I know we should use somehow flavors and quark model, but I don't ...
1
vote
1answer
40 views

Quarks and theory on nuclear forces [closed]

I wonder if there existed a complete theory describing the behaviour of quarks in nucleons and other baryons and mesons and the behaviour of gluons. Does QCD alredy describes it all in perfect detail ...
1
vote
1answer
59 views

Why do we need the strong interaction if we have Yukawa's meson theory?

How is Yukawa's theory of mesons different from the standard model's strong interaction? I mean if Yukawa's theory is complete then why do we need quarks and gluons?
4
votes
2answers
1k views

Is a quark bomb possible?

I am wondering about the possibility of making a bomb out of the binding energy of quarks inside hadrons. I know that about confinement and all that, but I wonder if there is a way to harness this ...
1
vote
1answer
98 views

Why do protons not break into quarks?

I know that free a neutron breaks into a proton because a proton has less mass and energy. Then, why do protons not break into quarks, since they have even less energy? Or why do gluons join quarks? ...
1
vote
0answers
15 views

T invariance in flavored meson system

Consider Kaon CP conjugate states $\left|K^{0}\right>$ and $\left|\bar{K^{0}}\right>$. The physical states i.e, eigenstates of effective hamitonian can be written as \begin{equation} ...
5
votes
2answers
1k views

If quarks didn't have mass, could protons (and neutrons) exist?

I read here (mass of a proton) that the mass of a proton is mostly (99%) due to the energy of the strong nuclear force which binds the quarks together, and not the actual mass of the quarks. My ...
3
votes
2answers
77 views

Does quark confinement imply indivisibility of quarks?

I recently heard the statement$^1$ that quark confinement is evidence for the indivisibility of quarks (i.e. that they are indeed fundamental and have no substructure), but I don't see any reason why ...
2
votes
1answer
43 views

Valence sea quarks parton distribution functions

There's somethin from Thomson (Modern Particle Physics) that I am a little mythed by. Section 8.4.3, eq. 8.3 is given as $$ ...