Questions tagged [strong-force]
The strong force or interaction is responsible for the confinement of quarks inside hadrons and the binding of nucleons inside a nucleon, and it is described by the gauge theory of QCD. It provides most of the mass of ordinary matter, which is dominated by the nucleons, proton and neutron: over 99% of the mass of these is attributable to the strong-force field energy. Use where technical details of QCD are not warranted.
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How does the exchange of pions result in the strong force?
I understand that the residual strong force is a result of an exchange of pions. But I fail to understand how this exchange results in a force that holds nuclei together! May this query please be ...
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How do we show that gluon-fields have color?
I understand how to derive the QCD lagrangian based on certain assumptions about Quark fields and $SU(3)$ gauge invariance and in the final expression one finds the term $(A_µ)^c*T_c$ where $T_c$ is ...
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When/ how were/are quarks formed?
We know that all particles can eventually be converted into energy. We know also that electrons were and still are formed by pair production from a 1MeV photon.
Do physicists have yet any idea how ...
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Unstable vs. stable nuclei plotted on a graph
The enclosed graph shows the number of Protons on the x-axis (Z), and the number of Neutrons on the y-axis for all elements (N). Stable combinations are marked by black squares, whereas unstable ones ...
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Isospin conservation for total isospin or third component of isospin?
In a strong interaction, is the total isospin or just its third component conserved? Or are they both conserved?
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Why does the weak nuclear interaction have a shorter range than strong nuclear interaction?
My textbook says:
"Weak nuclear interaction acts on protons, neutrons, electrons and neutrinos in order to bring about beta decay. It has very short range (10-18m)"
"Strong nuclear interaction ...
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Half-life of $W$ and $Z$ bosons
$W$ and $Z$ bosons should decay through weak interaction. But their half-life is around $\tau = 10^{-25} s$ which is a typical value for particles decaying through strong force (instead of a $10^{-12}-...
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What happens if a neutron flies towards a nucleus?
Rutherford experiment shows that alpha-particles when they fly towards metal foil sometimes (in minority of cases) can bounce. An explanation proposed was that atoms in fact have positively charged ...
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Do color changing interactions between up and down quark exist?
In our Standard Model course we wrote down the term for the quark-gluon interaction of the left handed $SU(2)_L$ quark doublet $q_L$ as: $\mathscr{L} = … + \bar{q}_L \gamma^\mu iG^a_\mu(x) \lambda^a ...
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What are chromoelectric and chromomagnetic fields?
Are they the normal electric and magnetic fields from Maxwell fields? Or are they just the corresponding components from $G_{\mu\nu}^a$ (the gluon fields), say chromoelectric fields are simply $G_{0i}^...
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Unification of the strong and electromagnetic interaction
Is it somehow possible to theoretically unify the electric charge in electromagnetic interaction with the colour charge in the strong interaction and how these charges give rise to the respective ...
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Antimatter: weak and strong forces
Antimatter is known to have equal mass to matter and opposite charge sign. Positron has the same mass as electron and opposite sign of charge, anti-proton has the same mass as proton and opposite sign ...
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A place of space-time where the only fundamental interaction will be the gravitational forces: does make sense?
We know that there are four (fundamental forces) fundamental interactions of nature, this Wikipedia.
I'm curious about if we can speculate that there exists a place of the space-time in which, after ...
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Bag model and MFT
Can I think of the MIT Bag model as an application of mean field theory (MFT) in nthe domain of nuclear physics? All the interactions between quarks are mediated via strong interaction, whose exact ...
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Why isn't there an universal nuclear model? [closed]
What problems does (low energy) nuclear physics face when trying to model the nuclear structure? Why isn't possible to have a theoretical model that can be used to describe any nucleus?
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What is the time period in which an interaction with a π-meson takes place?
The longer-range inter-nucleon force is not a direct result of the gluon field, but is indirectly affected by a quark-antiquark pair (meson).
If this ‘residual’ strong interaction between nucleons ...
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How are exchange terms in phenomenological nuclear potentials related to the exchange of nuclear force carrirer particles?
Consider a proton-neutron system.
Phenomenlogical nucleon-nucleon potentials contain exchange forces terms (Majorana, Bartlett and Heisenberg terms), which are linked to the symmetry of the state w.r....
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Why is the distance between two nucleons greater than the minimum energy point?
The potential energy associated to the interaction between nucleons has its minimum (point of equilibrium) at $r\sim 0.7 fm$, as showed in the following graph:
Nevertheless, there are two facts ...
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Does the strong force increase or decrease with aligned spins?
The deuterium exists only with the proton and neutron of aligned spin, which suggests that the residual strong force is greated with aligned spins, i.e. the binding energy is greater if the spins are ...
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Why is $SU(3)$ and not $U(3)$ the correct gauge symmetry? [duplicate]
If quarks come in three colours $r$, $g$ and $b$ than (neglecting all other quantum numbers and spacial freedom for now) a state of a quark would be a vector in $\mathbb{C}^3$.
If we are now looking ...
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Hadrons in realistic string phenomenology
String theory contains a number of models of baryons as branes, notably the Sakai-Sugimoto model. But I don't remember ever seeing a discussion of baryons, or any kind of hadron, in the specific ...
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Why does it take less binding force to hold the two atoms that a uranium atom has split into? [closed]
When a Uranium atom splits into two there is a little bit of mass left that is equivalent to a big amount of energy (e=mc^2) and it explodes in fission
It takes less binding force to keep the two ...
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Creating isotopes by shooting neutrons into an unstable nucleus [closed]
I've been doing a lot of amateur research lately (youtube videos) on particle physics and find it all really interesting. I'm also a crazy alien conspiracy theorist who believes in the whole "Bob ...
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Do all binding energies work like the exchanging force of photons but just in different strengths? [closed]
Do all Binding Energies use the same force but in different strengths?
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What is meant with an $X$ in the particle data booklet?
What is meant with the $X$ in some decay channel of the $B^0$ ?
B⁰ PDG Booklet
I imagine it could be an unidentified resonance, but I cannot find a definition. What especially confuses me is that ...
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Nuclear stability [duplicate]
Why does increasing the number of neutrons in a nucleus make it more unstable? I know that adding more protons increases electrostatic repulsion, therefore the nucleus is more unstable, but as ...
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Strong force gets weaker at small distances yet approximated by -1/r potential
My particle physics textbook (by Martin and Shaw) has confused me, it states in ch.7 that the strong force gets weaker at small distances, and that it can be approximated by $V(r) = -\frac{4 \alpha_s}{...
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Can a nucleus (made of neutrons) exist without an EM field?
I understand that the EM field has an EM charge and that a nucleus made of neutrons and protons has an opposite EM charge, and this attracts.
And because the electron's kinetic energy (that would ...
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What keeps quarks separate (strong force pulls, but what repels to equal out)
We know that the strong force keeps quarks together, that is mediated by gluons (and their charge is called color charge).
We know that the residual strong force keeps neutrons and protons together in ...
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How does mass of the exchange particles affect the range of a force? [duplicate]
I read an article asserting that nuclear force is a short range force because of gluon's mass, and EM force is a long range force because photons massless.
I also want to know, why quantum ...
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What is the force carrier for neutrons in fission?
Say I have a neutron capture event, leading to a fission reaction in which a few neutrons are expelled. These neutrons inherit a certain momentum from this fission reaction.
How do these neutrons ...
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What is the difference between a deuterium nucleus and a sexaquark?
Assume a sexaquark contains 3 up and 3 down quarks.
What is the difference between this and a deuterium nucleus containing a proton bound to a neutron?
Is there any difference?
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Inverse square rule for strong forces
Most of the forces induced by a point particle follows the $1/r^2$ rule. Then why does the strong force not obey it?
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No need for Strong force
As 3 quarks stay inside of proton, where down quark just opposite charge of up quarks then what would happen if I say both of them are attached by their own electromagnetic force instead of strong ...
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How would an interaction with a single charge, and a charged weightless carrying particle behave?
We learnt about, among the other three fundamental interactions, the strong interaction. The particles that are affected by it are those with color-charge. It's carrying particles, gluons, have a ...
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Error estimation of $\alpha_s$
I have calculated the strong coupling constant $\alpha_s$ using and approximate solution of the Renormalization Group Equation
$$\mu_R^2\frac{d\alpha_s}{d\mu_R^2}=-(b_0 \alpha_s^2 + b_1\alpha_s^3 + ...
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Question about the vacua of the Standard Model
This question is probably based on a misunderstanding. Please correct me if I'm wrong, and if unclear, I'll try to put it in a clearer language.
In Yang-Mills theory such as the theory of strong ...
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Anti-quark transformation
The center of $SU(3)$ is $Z_3$. So a quark transforms under an element $z\in Z_3$ in this center as $q\to q'=z q$. How do I figure out how the anti-quark $\bar q$ under this center? How about the ...
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What if we had a universe that contained only two particles held together by the strong force? [closed]
What if we had a universe that contained only two particles held together by the strong force?
What would be the behavior of the particles if the strong force suddenly vanished?
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Why don't protons collapse to a point?
If the quarks that make up the proton are point particles, and the forces binding them together is the strong force which is $137$ times stronger than the electromagnetic force (which makes the quarks ...
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How do nuclear transitions generate electromagnetic waves?
In my last question, Can stimulated emission happen in nuclear energy states?, anna v mentioned this in his/her answer:
This involves nuclear transitions, but the output is electromagnetic.
I ...
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What is the theoretical efficiency of fusion?
What is the theoretical limit of the amount of energy that can be extracted from a fusion reaction? I am not talking about the practical efficiency of a reactor, but rather what fraction of the mass-...
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If Baryons are subject to the strong nuclear force, how are they involved in Beta decay?
The question is really in the title with this one, I just need a little bit of clarity, consider beta-minus decay, which is an interaction governed by the weak nuclear force, $$n\to p^+ +e^- +\bar v_e$...
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How can an atom exist without electrons?
Consider ${\rm He}^{2+}$ as a example. It has 2 protons and 2 neutrons but no electrons. How is that ion can exist as an atom, and how can we account for its stability?
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Why and how does the term $\frac{\theta}{32\pi^2}F_{\mu\nu a}\tilde{F}^{\mu\nu a}$ induce electric dipole moment of the neutron?
It is well-known that the operator $$\delta \mathcal{L}_{QCD}=\frac{\theta}{32\pi^2}F_{\mu\nu a}\tilde{F}^{\mu\nu a}$$ violates CP, it can contribute to the neutron electric dipole moment, $d_n$. For ...
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Relation between Strong Forces and Binding Energy
The definition of Strong Force is the force that binds the quarks into the protons and neutrons, and spills over around each proton and neutron and is an attractive one.
And Binding Energy is the ...
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Counting gluons in a proton, are we sure measurement doesn't affect the number?
Regarding gluons in a hadron, when you look with one resolution you see a certain number, but looking closer you see some of these particles have split.
How are we actually looking at these? Can we be ...
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Protons and Neutrons inside the Nucleus
I know that the strong nuclear force holds quarks together to form protons and neutrons, as long as their color charges add up to white, so then how does the strong force simultaneously hold the ...
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Connection between QCD Lagrangian and the strong running coupling constant
I know the QCD Lagrangian as well as the running coupling constant for the strong force.
But how are they connected? The Lagrangian should contain the coupling constant, shouldn't it?
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Why is the strong interaction blind to the third component of Isospin?
Neutron and the proton have different values of $I_3$, the third component of the Isospin. Yet the strong interaction cannot distinguish between them. Why is this so? I can't understand this.
The ...
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