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

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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 ...
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4answers
115 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 $931~\...
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143 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 (...
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50 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 ...
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84 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 ...
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73 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 $qq$...
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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 ...
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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. ...
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47 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?
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121 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 ...
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124 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 = \frac{1}{\sqrt{2}}...
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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 ...
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1answer
41 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 ...
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1answer
61 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?
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124 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 decays,...
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1answer
105 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?
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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} \left|M_{a}...
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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 ...
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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 $$ \frac{F^{\mathrm{en}}_2(x)}{F^{\mathrm{ep}}_2(x)}=\frac{4d_{V}(x)+u_{V}(x)+...
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61 views

How often do quarks annihilate?

How often do quarks annihilate? Quarks bond frequently with quarks, and antiquarks bond frequently with antiquarks. So why do quarks not annihilate antiquarks extremely quickly? More to the point, ...
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267 views

Why do quarks tend to bond in groups of three?

Why do quarks tend to bond in groups of three? I understand why they might in bond in groups of three to create a net charge of zero (i.e. neutrons), but I don't understand why they form protons and ...
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Can the Higgs mechanism provide complex masses for quarks and neutrinos?

Can the Higgs mechanism give complex masses to quarks and neutrinos, or is only real mass generation possible? There exist complex phases in the CKM and PMNS matrices, can they be explained through ...
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Subnuclear reactions: combining quarks

When you try and pull two quarks apart, you don't get two separate quarks, but instead: the energy stored in the field between them gets high enough to create more quarks, and instead of two ...
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Why doesn't the color force between two quarks have an inverse square law?

From what I understand the color force between two quarks doesn't decrease with distance. Why is it that the color force doesn't decrease with the square of the distance if there are three dimensions ...
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Changing, or static, quark color composition within a proton?

Consider say the proton. It is seems to be universally stated that a proton is "composed of three quarks, 2 up and a down, and you must have the three different 'colors'". So, you can have blue-up, ...
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343 views

Where does a hadrons mass come from [duplicate]

So I've come to the understanding that a hadrons mass does not come from the constituent quarks but instead comes from a combination of things like binding energy and the mass energy of virtual gluons ...
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64 views

Evidence for standard model description of neutrons

as I don't know too much about experiments I have the following question concerning the evidence about the quark constituents in neutrons. After a quick google investigation I found some sentences ...
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Do particle accelerators centrifuge the quarks of a proton?

Is it right that circular particle accelerators use magnetic fields to deflect the particle beam? Using the simple equation of "a charged particle in a magnetic field": $\vec{f}=q\vec{v}\times\vec{...
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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 ...
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859 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 ...
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260 views

Can the up quark still be massless?

It used to be commonly discussed that the bare mass of the up quark can be $0$. This was because we can't observe its effect directly. To my knowledge the up quark can only be measured by its effect ...
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Quark model in particle physics

As we all know that baryons are made up of three quarks while mesons are made up of a quark and an anti-quark. Is it possible for a particle to exist with five or seven quarks? Can a particle exist ...
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107 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 ...
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226 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 ...
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1answer
88 views

What makes neutron heavier than a proton? [duplicate]

The mass of proton is 1.672*10¯²7 kg while it is 1.675*10¯²7 kg. Both are made up of 3 quarks each. Then what makes proton lighter than a neutron?
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Feynman rule for current-current operators

I wanted to know what is the Feynman rules for current-current vertex like this one: $$ {\cal{ L}} = G^\prime_F \hspace{2mm} \bar{d} \gamma^\mu (1-\gamma^5) u\hspace{3mm} \bar{s}\gamma_\mu (1-\gamma^...
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How and why the phrase “quark force increases with distance”?

I have seen that phrase "force between quarks increases with distance" at many resources, some even relatively credible (albeit written for general audience). What is the reason behind that, when ...
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244 views

The Makeup of the Pentaquark

Why is it that when they have the artist's rendition of the Pentaquark it shows two downs, two ups, and one anti-strange quark? Is this or is this just for show? Follow up to this question: if this ...
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How do quarks have no spatial extent?

I found an answer to a question I had and that is that quarks have no spatial extent. But how is that possible? Everything has to have some spatial extent; to keep continuing on and on, right?
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Pentaquark spin prediction

Is there a straightforward way to see what the spin of the recently-discovered pentaquark states should be, from the representation theory of $SU(3)\times SU(2)\subset SU(6)$? I can see that from the ...
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1answer
178 views

How many combination can quarks form?

How many different combinations can quarks produce? E.g. 2 up quarks + 1 down quark = proton. Is this value going to be infinite?
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heavy quark pair spin states

Apparently, heavy quark pair can have "axial-vector" spin state, "vector" spin state, and two different "tensor" spin states. Can anyone explain to me what they are and why this is the case? Thank ...
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1answer
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Is there a theoretic temperature where single quarks might become individually stable?

This question is what lead me to ask this. Strong force between quarks that are out of causal contact and my understanding of the standard model is that the answer is no - but the standard model ...
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Strong force between quarks that are out of causal contact

This is a rather artificial scenario, but it has been bugging me lately. Background Due to the confinement in QCD, quarks are bound in color-neutral configurations. Any attempt to separate a quark ...
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1answer
204 views

Particle Physics Decay Question - Eta Prime Decay Parity/Angular Momentum Conservation

I was hoping someone could clarify why the following decay does not occur: $ \eta ^{'0} \rightarrow \pi ^{0} + \rho ^{0}$ The quark compositions and spin parity are as followed: $ \eta ^{'0} : (u\...
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274 views

What is the motion of quarks inside nucleons? [duplicate]

Nucleons consist of quarks which are charged particles. Proton has the quark content of uud and neutron of udd. So, it may be visualized that the down quark always remain between the up quarks inside ...
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Quark decay implies particle decay?

For example, since $$s\rightarrow u+\overline{v_e}+e^{-}$$, then sticking a $\overline{u}$ next to the quarks ($s$ and $u$) we get $$s\overline{u}\rightarrow u\overline{u}+\overline{v_e}+e^{-}$$, ...
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Is there a quark conservation law?

The section on particle interactions in my revision guide says that only the weak interaction can change quark types, e.g. when a neutron changes to a proton the down quarks in the neutron are changed ...
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432 views

How to tell if a particle interaction is strong/weak?

Problem: Prove that the reaction $p+p\rightarrow p+K^+$ is impossible, where $p=\text{proton}$, $K^+=\text{kaon}$. (Side question: Is there a specific name for a positive Kaon, just like a "positive ...
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Do quarks violate quantization of charge?

Does existence of various kinds of quarks like up, down, strange, charm, top, bottom violate the quantisation of charge or just redefine it as up quark have charge +2/3 and have -1/3. Or do things get ...