All Questions
Tagged with quantum-chromodynamics mesons
29
questions
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What is vector meson dominance and why is that related to QCD having a repulsive potential?
At long distances QCD is said to give rise to attractive force between nucleons by pion exchange and to give rise to repulsive force at short distance mediated by vector mesons. Is there a ...
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62
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Why does the Yukawa potential fail for the strong force? [duplicate]
The gluon is a massless particle, so according to the Yukawa potential the strong force should have a $r^{-1}$ potential. However, that is clearly not the case.
Is it because the gluons themselves can ...
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2
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66
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Mass of the kaon (1460)
When looking at the particle listing in PDG most of the hadron masses and excitation include an experimental error. But this is not the case for the Kaon (1460), does anybody know why? This means the ...
- 21
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Meson-Meson Scattering Data
Recently, I have been interested in the scattering amplitudes of mesons in the high-energy fixed-angle regime. I have come across a simple result, due to Brodsky et al., that predicts the scaling of ...
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Structure functions for mesons
I was researching about structure functions and understand how it's a probability density function that describes the distribution of quarks inside hadrons. However, since mesons also have quark gluon ...
- 625
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How Does QCD Explain Nuclear Fission?
This question is brief and simple. As a layman, it is my understanding that QCD (Quantum Chromodynamics) explains the nuclear force as a "residual" force, mediated by pions (mesons), which ...
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2
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In the history of the development of the standard model was there a version in which quark-antiquark pairs or flux tubes were the fundamental particle [closed]
Based on the observations of color confinement and no free quarks, I'm wondering if instead of a having quarks as fundamental particles, during development of the Standard Model was there ever a ...
- 518
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2
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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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Meson masses difference
I am reading some group theory applied to QCD and they show how by using the lightest 3 quarks in the $l=0$ state we get 9 pseudoscalar mesons and 9 vector mesons. The difference in masses between the ...
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Why is a quarkonium any different from a meson?
Quarkonium states are bound states of a quark-antiquark pair but so do the mesons. What is the difference between a quarkonium (e.g., charmonium, and bottomonium) and a meson then? Why use a separate ...
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Understanding some lines from 't Hooft's paper on large-N QCD in 1+1d
In 't Hooft's paper "A two-dimensional model for mesons", the author shows that two-dimensional (1+1) QCD in the large-N limit interestingly gives a theory of mesons. 't Hooft calculates the "mesonic ...
- 5,371
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350
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Comparison between $\rho^0$ and $J/\psi$ decay mode
Why must a hadronic decay of the $J/\psi$ meson include (at least) three gluons? Why is the decay mediated by a single gluon allowed for the $\rho^0$ meson?
6
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How are the 'physical' isospin zero states determined?
Consider the light mesons. Since $3 \times \bar{3} = 8 + 1$, the states should be grouped into $\mathfrak{su}(3)$ octets and singlets. In the case of the spin zero states (the pseudoscalars), the ...
- 103k
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vector mesons identified with positive parity
I have seen in some sources (like in https://arxiv.org/abs/1610.06090, page 11, footnote 11 but also in some few more) that vector mesons are assigned with positive parity $(J^P)=1^+$. In Particle ...
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Which mesons are possible?
That's probably a plain question but I wonder: Which mesons can exist? The only limitation I'm aware of is the charge (antiparticle+particle). Ok, finally also the color (anticolor+color) but I assume ...
- 1,507
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Wavefunctions of (Pseudo)-scalar/vector meson and Tensor meson
Two quarks can bound to form a meson, and the wavefunction consists of several quantum degrees of freedom:
$$
\psi=\psi(\text{flavor})\psi(\text{color})\psi(\text{orbital})\psi(\text{spin})
$$
...
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Are bottomonium and charmonium the only quarkonium systems?
I had a question:
Are bottomonium and charmonium the only quarkonium systems?
I was searching the internet and found that these two systems have been experimetally observed but the toponium has ...
- 4,954
3
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403
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Scalar pseudo-Goldstones from hypothetical $SU(3)_V$ symmetry breaking in QCD
The eight light pseudoscalar mesons of QCD are the pseudo-Goldstone bosons of the spontaneously broken chiral (axial) $SU(3)_A$ quark flavor symmetry.
If we consider the hypothetical case of also ...
- 1,783
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What's the difference between a meson and a glueball?
There is a blog post by Matt Strassler about the structure of hadrons.
He contrasts the "conventional" picture of hadrons shown below:
with one that he considers to be more accurate:
From the ...
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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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Vector mesons as background gauge fields
Suppose we have some complicated fundamental theory of fermions and gauge fields which involves global chiral symmetry and global anomalies which breaks some subgroup of this symmetr. At some energy ...
- 8,901
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504
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Mass and wave function renormalization In chiral perturbation theory
Before I put forward my actual question, I think it will be useful to set the context in a clear way and that involves my understanding of a few very basic things of Chiral Perturbation Theory.
...
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Interpretation of vector mesons in QCD
It is well-known that scalar mesons are interpreted as pseudogoldstone bosons which is connected with spontaneous broken $SU(3) \times SU(3)$ symmetry to $SU(3) \times SU(3) / SU(3)_{chiral}$.
Is ...
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How to calculate D0->K+K- decay with QCD factorization?
I am studying the decay of D0->K+K- and I calculated the result of Branching Ratio by Naive QCD and I wrote all the equations for amplitude and branching Ration and Hamiltonian and... for this decay ...
6
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249
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Semileptonic decays of the $B_c$ meson
I am struggling with calculating the exclusive semileptonic $B_c^+\rightarrow J/\psi l^+\nu_l$ decay. I learnt that the amplitude is given by a product of the leptonic current $L^{\mu}$ and the ...
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String breaking in QCD
I have trouble understanding string breaking in QCD. I have read an article on arxiv (http://arxiv.org/abs/hep-lat/0505012), and I still don't understand what truly happens.
My understanding of ...
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202
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Probability of forming mesons vs baryons
When a heavy quark hadronizes it has some probability of forming a meson vs forming a baryon. I suspect there is a well known branching ratio for each type of hadron. Does anyone know what the ...
- 8,995
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386
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Are mesons color polarized?
The binding of quarks in mesons baffles me. It's an Occam's Razor thing.
Since a meson is a colorless, the simplest way to bind its two quarks together is to use a $U(1)$ Cartan subalgebra of $SU(3)$. ...
- 22.1k
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Does the color of a quark matter in a meson?
QCD and confinement specify that hadrons must be color-neutral. My understanding is that this means you can have mesons (quark + antiquark) or baryons with 3 quarks, one of each color: Red+green+blue=...
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