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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Why doesn't a nucleus-like body made up of just neutrons exist?

We know that neutrons exert short ranged nuclear forces over other nucleons in a nucleus, and these forces are only attractive in nature. Also this force is universal and doesn't differentiate between ...
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Why did the quark epoch occur earlier than the lepton epoch?

I don't understand the reason and hypothesis behind why the quarks appeared first—as per the big bang cosmology—shortly after the strong and electroweak force separated. We don't know what the quarks ...
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Non-relativistic quark model, baryon masses and potential

Is there a simple non-relativistic quark model, based on which baryon masses, especially for the nucleon and the Delta resonance can be calculated? What is a reasonable non-relativistic potential? Is ...
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On $\Delta^{+}$ particle decay

Using isospin notation $$ \Delta^+=\left|\frac 3 2,\frac 1 2\right\rangle=\frac{1}{\!\sqrt{3}}\bigg(|duu\rangle+|udu\rangle+|uud\rangle\!\bigg) $$ It is known all of the $\Delta$ baryons with mass ...
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Does the energy of the strong force have mass? [closed]

The mass of a proton is said to predominantly be "comprised" of the mass of the strong force interactions within the proton. Logically, one could conclude that the energy (the strong force ...
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Strength of strong force and electromagnetic force

In this link, it is claimed that the strength of the strong force w.r.t. the E&M force is about 137 times larger. Does this have anything to do with the fine structure constant?
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If isospin is conserved in a given strong interaction, can we say that the interaction is certainly allowed?

If isospin is conserved in a given strong interaction, can we say that it is certainly allowed and it's not needed to check other conservation rules like baryon number, electric charge etc. ?
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How did Ernest Sternglass’ phenomenologically incorrect model of the neutral pion predict its mass and lifetime so accurately?

In 1961, Ernest Sternglass published a paper where, using what seems to be to be a combination of relativistic kinematics and Bohr’s old quantisation procedure, he looked at the energy levels of a set ...
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What would happen in a hypothetical universe without the other forces other than gravity? [closed]

What would be the rules of a hypothetical universe where there is only gravitational force, and weak strong and EM force do not exist? What would be the consequences of that?
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Strong nuclear force in fusion

I have read that there is an increase in the amount of the binding energy from the reactant nuclei and the product nucleus during nuclear fusion and this causes the decrease the internal energy (...
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Cause of Strong force

What is the origin and cause of the strong interaction which occurs between the nucleons? I have read that it is caused by the exchange of mesons but what then ultimately causes this meson exchange to ...
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Are "resonances" we are finding all in ground states or not?

Sometimes scientists are finding new compound particles as "resonances", i.e. short living complexes of constituent particles. For example dineutron was found as resonance with lifetime of $...
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Nuclear FISSION origin

Neutrons and protons consist of quarks, and when a neutron and a proton are squeezed tightly enough together, the quarks in each begin to interact and cause them to attract one another. The resulting ...
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Do alpha decays or strong-mediated decays like 'resonances' happen more slowly at colder temperatures?

At close to absolute zero, with less motion of the particles, could unstable particles that decay due to being 'pushed apart' by the electromagnetic force or the strong interaction last longer? I'm ...
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Is $SU(3)$ (and not $U(3)$) the symmetry group of color interactions because $U(1)$ is already used for EM?

I have already seen this question. It was answered that $U(3)$ can be decomposed into $SU(3) \times U(1)$, and $U(1)$ is already used for the EM interaction. Still, I wonder why the EM interaction ...
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Why is there no stable nucleus with two or more neutrons but no protons? [duplicate]

Why is there no stable nucleus with two or more neutrons but no protons?
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Why we do not get naturally occurring elements with atomic number greater than 92? [duplicate]

Why we do not get naturally occurring elements with atomic number greater than 92? I know that some arguments suggests that the reason is that all the elements with atomic number from 93 are highly ...
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What percentage of a Proton's mass is potential/kinetic energy?

So in an hydrogen atom, the total mass of the atom is equal to the masses of the proton, the electron, minus their net binding energy of around 13 eV. Making the total less massive than the sum of its ...
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Do all hadrons experience the strong nuclear force?

In nuclear physics, nuclear force, also known as the residual strong force, is mediated by pions exchanged between protons and neutrons. It doesn't seem like this should be limited to protons and ...
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Can we say that binding energy is the work done by the strong nuclear force?

I know that the strong nuclear force is the force that holds the nucleus together by overcoming electromagnetic repulsion between protons. Binding energy is the minimum energy that is required to ...
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Questions about Yukawa Potential for Strong Force

Here is what I have understood about the strong force: This is a close range force which acts on two charges. The way it works is that a charge releases a meson which attracts the two charges together ...
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How strong nuclear force become repulsive at distance less than 0.7fm? What is its mechanism? [duplicate]

I read many times that strong force become repulsive at distance less than (0.7×10^-15 m) but no-one explains how? and what is its carrier particle? what is its mechanism? I searched for answers so ...
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Changing electromagnetic and strong coupling in tandem?

It has been widely said that if $\alpha$ were to increase by only a few percent, life would be impossible because of the lack of carbon production in stars--and if it is increased too much, ...
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Is a 6-quark particle viable?

It is my understanding (which may be flawed) that protons and neutrons are stable because the 3 (R, G, and B) quarks form a "white" color singlet. Wouldn't 6 quarks or even 9 quarks create ...
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What are the weak force and strong force and higgs constants?

We use the SI System of measurement which is a human made system. In order to accurately describe forces/fields in nature we need to use certain experimentally determined constants to "scale"...
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Griffiths Elementary Particles Eq. 8.48 Chromodynamics 2nd edition

Griffiths describes the quark-antiquark amplitude (First order approximation considering its Feynman Diagram page 289) as similar to the electron-muon amplitude. He compares them in a way such that ...
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How do the strong and weak forces relate to nuclear fission and fusion?

Fission and fusion are due to the strong and weak forces, but it is unclear to me which is responsible for which.
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Why should the EM interaction cause a mass difference between neutron and proton but not between $u$-quark and $d$-quark?

The reason why the $u$-quark and the $d$-quark have different masses is that they couple with different Yukawa coupling strengths to the Higgs field. My understanding is that this is the sole reason ...
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How can the strong force, which is conservative, not follow the inverse square law?

In terms, which someone with a background in chemical physics & quantum chemistry might understand, what is the evidence that the strong force, across whatever its range is, follows something ...
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How do Fermi-Dirac statistics contribute to fermions in the Pauli Exclusion Principle?

So I’m doing some research on Quantum Chromodynamics and I've come to an area in which I’m having some trouble arriving at a conclusive answer. Apparently the Pauli exclusion principle states that no ...
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What units is strong nuclear charge measured in? [duplicate]

Do particles have a strong nuclear charge in the same way as they have electric charge? If so what unit would be used to measure this? Would it be measured in Coulomb for instance?
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Do gluons mediate the interactions between different flavors of quark?

From some of the quite professional sources (Basics from QCD by CERN; QCD from PDG), the QCD lagrangian is written in the form of $$ L = \Sigma_{f} \; \bar{\psi}^{(f)} i \gamma^\mu D_\mu \psi^{(f)} + ...
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How can I visualize the oxygen nuclear charge density?

Oxygen has 8 protons and 8 neutrons. Based on the nuclear shell model, protons should pair with anti-parallel protons to create singlet spin states, and neutrons should similarly pair with anti-...
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How can the strong nuclear force (QCD) be considered to violate chirality, but not parity?

Chirality is related to parity, correct? It is a form of 'parity'? So, How can the strong force violate chirality symmetry, but only the weak force violates parity symmetry? I am confused about the ...
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What mechanism gives mass to gluon balls? [duplicate]

Glueballs are hypothetical, real (non-virtual) particles made up of gluons, the particle of the gluon field that interacts with quarks. The gluons have a color charge themselves and they can form a ...
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How do virtual particles cause an attraction? [duplicate]

How do virtual particles such as photons cause a force between particles such as an attraction between protons and electrons?
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Why does the binding energy per nucleon rise as the nucleon number rises, then go down again, with nuclei heavier than iron? [duplicate]

As the strong nuclear force is a short range force, and as it is way stronger than Coulomb force, Lumen Learning answered my question as follows: “for low-mass nuclei, the nuclear attraction dominates ...
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Is nuclear force always attractive?

I read in my high school physics's textbook that nuclear force holds the nucleus. Is the nuclear force another name for the strong force? If it holds the nucleus it should be attractive. Am I right?
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Does the nuclear interaction favour aligned or anti-aligned spins?

My particle physics lecture notes seem to have contradictory statements. Firstly they argue that p-n is stable while p-p and n-n are not because the nuclear interaction favours spin alignment (and by ...
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Does pionium decay in massless QCD?

The bound state of ${\pi}^+ {\pi}^-$ is called Pionium. Is Pionium an Electromagnetic bound state or a Strong Force one? then Why? Does such a bound state last forever if one works in QCD with ...
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Is electric potential energy responsible for energy release in nuclear fission and nuclear potential energy in fusion? What if elec. force not exist?

It was my doubt and I thought it may be electric potential energy which is responsible for energy release in nuclear fission and by bombarding neutron we only provide energy to nucleons to cross ...
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Low energy strong coupling asymptotic

The low-energy behavior ($Q^2<\text{1GeV}^2$) of the strong interaction coupling constant predicted by LFHQCD, $\alpha_S = \pi \exp(-Q^2/4\kappa^2) $, where $\kappa=M_\rho/\sqrt{2}$, is in ...
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Do the “$SU(3)$ colors” live in a 3-dimensional vector space?

Previously I asked a question about the visualized colors: Do the "colors" live in a 3-dimensional vector space? (My earlier question is unfortunately closed) Now I like to ask the “$SU(3)$ ...
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How can the graviton spin-2 string have emerged from the strong interaction, mediated by spin-1 gluons?

The origin of string theory can be traced back to 1969: String theory was first studied in the late 1960s as a theory of the strong nuclear force, before being abandoned in favor of quantum ...
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How does the strong force increase in attraction as particles move farther away?

I have heard that the strong force can be imagined similar to a rubber band, where the farther you extend the ends, the harder they pull themselves back together. My question is how? From what it ...
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Can strong and weak "forces" manifest in Newton Units?

The Newton unit ($\text{N}$) is a unit of force on a macroscopic scale: $$1\text{N} = 1 \text{kg m/s}^2.$$ Gravity has so-called the gravitational forces (such as shown in the Newton theory of ...
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What is the equation for the non-constant coupling $\alpha_s$ for the strong force?

I wanted to ask the question Is there an equation for the strong nuclear force? but someone already has. The top answer gives $$V(r) = - \dfrac{4}{3} \dfrac{\alpha_s(r) \hbar c}{r} + kr$$ It is ...
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Why is the alpha particle in alpha decay considered to be in a potential well?

I understand that when modelling alpha decay, it is useful to consider the $\alpha$ particle as being preformed, in a region confined to the daughter nuclei. I also understand that the term $V_{0}$ ...
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Why is residual strong force needed?

I was wondering why the residual force was needed to hold nucleons together? If the net charge resides on the surface and acts perpendicular to the surface (page I found, though not about nuclei), how ...
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Behaviour of Nuclear Force

If nuclear force is attractive, then why the nucleons don't collide with each other? I think about this, but do not get any proper answer?
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