The quarks tag has no wiki summary.
17
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4answers
1k views
Could the Periodic Table have been done using group theory?
These three questions are phrased as alternative-history questions, but my real intent is to understand better how well different modeling approaches fit the phenomena they are used to describe; see 1 ...
11
votes
1answer
374 views
How to determine the mass of a quark?
As far as I know quarks are never found in isolation, so how can we determine their rest mass?
10
votes
4answers
2k 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 ...
10
votes
1answer
142 views
Magnetic monopoles
I am a non-expert in this field, just have a layman's interest in the subject. Has anyone ever considered the possibility of magnetic monopoles (one positive and one negative charge) being confined ...
9
votes
3answers
916 views
What does it mean that the neutral pion is a mixture of quarks?
The quark composition of the neutral pion ($\pi^0$) is $\frac{u\bar{u} - d\bar{d}}{\sqrt{2}}$. What does this actually mean?
I think it's bizarre that a particle doesn't have a definite composition. ...
8
votes
2answers
1k views
Is it pions or gluons that mediate the strong force between nucleons?
From my recent experience teaching high school students I've found that they are taught that the strong force between nucleons is mediated by virtual-pion exchange, whereas between quarks it's gluons. ...
8
votes
1answer
368 views
Do color-neutral gluons exist?
If I'm correct a quark can change color by emitting a gluon. For example a blue up quark $u_b$ can change into a red up quark by emitting a gluon:
$$u_b \longrightarrow u_r + g_{b\overline{r}}$$
...
8
votes
2answers
249 views
What IS Color Charge?
This question has been asked twice already, with very detailed answers. After reading those answers, I am left with one more question: what is color charge?
It has nothing to do with colored light, ...
7
votes
1answer
469 views
What is the difference between 'running' and 'current' quark mass?
When looking at the PDG, there is a difference between the 'running' and the 'current' quark masses.
Does anyone know which is the difference between these two?
6
votes
3answers
200 views
Origin of lepton/quark generations?
What theoretical explanations exist for the fact that there are three generations of leptons and quarks?
I'm not so much asking why there are exactly 3 generations, but rather what makes electron, ...
6
votes
2answers
336 views
Neutrino oscillations versus CMK quark mixing
I wish to describe in simple but correct terms the analogy between the Cabibbo–Kobayashi–Maskawa (CMK) and Pontecorvo–Maki–Nakagawa–Sakata (PMNS) matrices.
The CMK matrix describes the rotation ...
6
votes
1answer
57 views
Measuring nucleons using electron beams
sorry if the question is too elementary. From: The Britannica Guide to Particle Physics:
The sizes of atoms, nuclei, and nucleons are measured
by firing a beam of electrons at an appropriate target. ...
5
votes
2answers
62 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 ...
5
votes
2answers
340 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 ...
4
votes
2answers
230 views
About free quarks and confinement
I simply know that a single free quark does not exist. What is the reason that we can not get a free quark?
If we can't get a free quark then what is single-top-quark?
4
votes
4answers
5k views
What are quarks made of?
So atoms are formed from protons and neutrons, which are formed from quarks.
But where do these quarks come from? What makes them?
4
votes
1answer
226 views
How to count quarks using Deep Inelastic Scattering?
The Wikipedia article on deep inelastic scattering suggests that the experiment shows baryons have three point of deflections (corresponding to three quarks) and mesons have two points of deflection.
...
4
votes
1answer
91 views
Asymptotic Freedom - Qualitative Explanation
I am doing a (mostly qualitative) course on Particle Physics, and am confused about the concept of asymptotic freedom. The lecture notes basically say that a quark may experience no force/be "unbound" ...
4
votes
3answers
135 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.)
4
votes
2answers
150 views
How can a pion have a mass, given it's a “field mediator” and created/destroyed continuously?
Maybe some of my assumptions here are basically wrong, but isn't it true that
pion is the "mediator" for the strong force field.
the quantum field theory basically says that there are no fields, ...
4
votes
1answer
298 views
How does Delta baryon decay conserve angular momentum?
I'm a chemist so bear with me:
I understand the Delta baryons $\Delta^{+}$ and $\Delta^{0}$ to be in some sense spin (and isospin) quartet states of the proton and neutron. These can decay straight ...
4
votes
1answer
85 views
Why is a pion so light compared to a neutron or proton?
A pion is made out of a pair of up and/or down quarks. A neutron or proton is three up or down quarks. So naively I'd expect a pion to be about 2/3 the mass of a nucleon.
In fact it's less than 1/6 ...
4
votes
2answers
81 views
What reason(s) exist to suppose that all degeneracy pressures can be overcome in Black-Hole formation?
In models of stellar collapse to a black hole, it is a given that density increases without bound towards a singularity. Electron degeneracy I get. Neutron degeneracy I get. I assume there's some ...
3
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2answers
540 views
What Quark and Anti-quark are electrically neutral Pions made out of?
A positive pion is an up and an anti-down. A negative pion is a down and an anti-up. What's a pion with an electrical charge of 0?
3
votes
1answer
40 views
What is the $t\bar{t}$ production supposed to bring up
The $t\bar{t}$ production, I've read, that will somehow confirm the QCD and might bring up new physics. Why are we studying $t\bar{t}$ production from $p-p$ collisions at the LHC?
What are we trying ...
3
votes
1answer
88 views
Is there a tb meson?
I was wandering around the particle date group page for meson and couldn't find a meson for top-bottom, which from symmetry you would expect.
Q1: Is this because it hasn't been found?
Q2: There is ...
3
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0answers
82 views
Can quark-gluon plasma ever be close to an ideal gas of asymptotically free quarks?
The question inspired by an upcoming colloquim at UCB.
A naive interpretation of quark asymptotic freedom seems to imply that at high enough energies they should be weakly interacting. On the other ...
2
votes
5answers
256 views
Could Quark model turn out to be false?
Quarks combine to form composite particles called hadrons, the most stable of which are protons and neutrons, the components of atomic nuclei.
Due to a phenomenon known as color confinement, quarks ...
2
votes
2answers
147 views
Is there anything smaller than a quark? [duplicate]
I've gotten interested in physics recently due to the many educational channels on YouTube such as sixtysymbols and minutephysics. They talk about quarks sometimes, and I was wondering if there is ...
2
votes
1answer
192 views
What is meant by the rest energy of non-composite particle?
When talking about the rest energy of a composite particle such as a proton, part of the rest energy is accounted for by the internal kinetic energy of its constituent quarks. But what is physically ...
2
votes
1answer
173 views
Why are the quarks so named?
Quarks have a variety of names (or flavours):
Up
Down
Strange
Charm
Bottom or Beauty
Top or Truth
Why do they have such odd names?
2
votes
1answer
90 views
$sss$ decay and violation of strangeness
Why can the hyperon $\Omega^{-}$ not decay by strong interaction? It seems that strangeness must be violated, but why is it the only way?
2
votes
0answers
107 views
Strong decays of baryons via quark-antiquark pairs
I have the doubly charmed $\Xi_{cc}^{++}$ consisting of ccu quarks.
This is meant to decay via strong force, producing a light baryon (cud/uuc/udc etc...) and a quark-antiquark pair along with a ...
2
votes
0answers
108 views
What forms are theoretically predicted for orbitals or quarks in hadrons and of hadrons in tritium?
We all know very illustrative spatial representations of predicted electron orbitals in atoms which are essentially spatial plots of the solutions of wave equations.
In all atoms the electrons occupy ...
2
votes
0answers
112 views
What is new with quark-Gluon Plasma and the bubble formed at RHIC?
RHIC experiment results of forming Quark-Gluon Plasma and a possible bubble was news few months ago. I cannot find any follow up news after that. Does anybody know anything new in this front? I am ...
1
vote
2answers
162 views
So there are 6 quarks, what are anti-quarks considered then?
I just recently got into particle physics and the quantum world and I love it.
So my first big question is.
I watch all these videos and people explain the quarks (up, down, top, bottom, strange, ...
1
vote
2answers
259 views
Quark compositions in $\pi^+$ to $\pi^0$ pion decay
Pions can undergo a rare beta-like decay into leptons:
Pion beta decay (with probability of about $10^{−8}$) into a neutral
pion plus an electron and electron antineutrino (or for positive
...
1
vote
2answers
111 views
What is mass of free up and down Quark?
Quarks combine to form composite particles called hadrons, the most stable of which are protons and neutrons, the components of atomic nuclei. Due to a phenomenon known as color confinement, quarks ...
1
vote
1answer
62 views
The fractional model of Quarks electric charge was found before discovery of the $\Delta^{++}$, or after it?
From Wikipedia:
Existence of the $\Delta^{++}$ , with its unusual +2 electric charge, was a crucial clue in the development of the quark model.
the fractional model of Quarks electric charge was ...
1
vote
1answer
132 views
Particle mixing and indistinguishability
Neutral kaons have two flavor combinations: $\mathrm{d}\bar{\mathrm{s}}$ and $\mathrm{s}\bar{\mathrm{d}}$. They can also be weak eigenstates: $\mathrm{\frac{d\bar{s} \pm s\bar{d}}{\sqrt{2}}}$.
But ...
1
vote
1answer
576 views
Quantum numbers of the helicity states of the W boson
What are the weak hypercharge and weak isospin quantum numbers of the helicity states of the $W^\pm$ and $Z^0$ bosons?
The W boson is a spin-1 massless particle. Consequently it has three helicity ...
1
vote
3answers
84 views
Top quark production questions
I am just looking on the TopQuark production via proton antiproton collision and strong interaction. There seem to be three basic possibilities.
$q + \bar q \rightarrow Gluon \rightarrow t +\bar t ...
1
vote
1answer
50 views
Quarks and anti-quarks forming particles [duplicate]
As I know, when particles and anti-particles come close, they anihilate. So somthing caused me a big trouble : how can particle formed by quarks and anti-quarks can exist? I've just found some mesons ...
1
vote
1answer
94 views
A strange particle, $X$, decays in the following way: $X → π^– + p$. State what interaction is involved in this decay
A strange particle, $X$, decays in the following way: $X → π^– + p$. State what interaction is involved in this decay.
I know the answer to be weak interaction, but why is it weak interaction? What ...
1
vote
1answer
200 views
What was the first discovery of the delta baryon $\Delta^{++}$?
The delta baryons (also called delta resonances) are a family of subatomic hadron particles which have the symbols $\Delta^{++}$, $\Delta^{+}$, $\Delta^{0}$, and $\Delta^{−}$ and electric charges +2, ...
1
vote
1answer
102 views
Relating theta_QCD to neutron EDM
How do I relate the topological $\theta_\text{QCD}$ parameter to the electric dipole moment (EDM) of the neutron?
I am very familiar with chiral perturbation theory. I just need to know how to take ...
1
vote
1answer
323 views
Quark Radius Upper Bound
If quarks had internal structure (contradicting current beliefs), what is the lowest
upper bound on their "radius" based on current experimental results?
If possible, I'd prefer to only consider ...
1
vote
1answer
90 views
Could quarks and leptons mix if they carried flavor charges?
If quarks and leptons carried flavor charges that differed across generations (as they do in some theories), then could mixing take place?
1
vote
1answer
69 views
Baryon wave function symmetry
If a baryon wavefunction is $\Psi = \psi_{spatial} \psi_{colour} \psi_{flavour} \psi_{spin}$,
and we consider the ground state (L=0) only.
We know that the whole thing has to be antisymmetric under ...
1
vote
2answers
117 views
Second baryon octet
Let's temporarily ignore spin. If 3 denotes the standard representation of SU(3), 1 the trivial rep, 8 the adjoint rep and 10 the symmetric cube then it's well-known that
3 x 3 x 3 = 1 + 8 + 8 + 10
...
