Binding energy between nucleons vs BE inside nucleons

Click For Summary

Discussion Overview

The discussion revolves around the concept of binding energy in the context of nucleons and their constituents, specifically comparing the binding energy that results in the mass deficit of a nucleus to the mass excess of protons and neutrons due to their constituent quarks. The scope includes theoretical aspects of nuclear and particle physics.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant notes that the mass of a nucleus is less than the sum of the masses of its nucleons due to binding energy, which is relevant for energy release in fusion and fission.
  • Another participant questions why the binding energy of a nucleus decreases mass while the binding energy within a proton or neutron increases mass.
  • A later reply explains that the mass of a nucleus is smaller due to negative binding energy, referencing the semi-empirical mass formula and the repulsive potential at short distances between nucleons.
  • This reply further elaborates that the mass of a proton is greater than the sum of its constituent quark masses due to the potential and kinetic energy of quarks, as well as the presence of dynamical quarks that contribute additional mass through energy fluctuations.
  • The concept of confinement of quarks and the generation of mass through quark-antiquark pairs is also introduced, highlighting the complexity of mass generation in hadrons.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between binding energy and mass in nucleons versus nuclei. While some explanations are provided, no consensus is reached on the underlying reasons for the contrasting effects of binding energy.

Contextual Notes

The discussion includes assumptions about the nature of binding energy and the role of quarks, which may not be fully defined or agreed upon by all participants. The complexities of quark dynamics and their contributions to mass are acknowledged but not resolved.

alexbib
Messages
62
Reaction score
0
humm, I've been wondering:

the mass of a nucleus is less than the sum of the masses of the constituent nucleons because of the binding energy. This is how we can get energy out of fusion and fission events.

on the other hand, the mass of a proton or a neutron is MORE than the sum of the masses of the constituent quarks.

Afaik, both the binding of a nucleus and the binding of a proton are consequences of the strong force, so how come one type of binding increases the mass while the other type decreases it?

Thanks.
 
Physics news on Phys.org
come on, nobody knows?
 
Well the case of the nucleus mass being smaller then the constituent nuclei is indeed due to the negative binding energy. This is shown by the semi-empirical mass formula. The nucleon-nucleon potential becomes repulsive at very short distances.

Now, let us look inside a nucleon :

The sum of the constituent quarkmasses is much smaller then the mass of the hadron. The extra mass comes from the potential and kinetic energy of the quarks and also from dynamical quarks.

For example the proton contains three valence quarks of three different colours (red, green and blue), but it also contains dynamical (sea) quarks. These are quark-antiquark pairs that appear and disappear through energy fluctuations in the vacuum.

These dynamical quarkpairs will generate mass. The mass of a hadron is bigger then the sum of the masses of the constituent quarks (the three quarks of the proton). But the dynamical quarks also generate mass (via symmetry breaking) , so in the end the mass of a proton is BIGGER then the sum of the three quark masses.

Keep in mind that the three quarks are confined, yielding a rise in their linear potential (dominant in the long range). Once a certain distance is exceeded there is enough energy to create a quark antiquark pair


marlon
 
Last edited:
ps check out the link in the latest entry of my journal

marlon

https://www.physicsforums.com/journal.php?s=&journalid=13790&action=view
 
Last edited by a moderator:
Alright, it does indeed make sense.
Thanks a lot!
 

Similar threads

Undergrad Why the binding energy per nucleon has specific pattern?
  • · Replies 2 ·
Replies
2
Views
3K
Undergrad How Does Binding Energy Relate to Nucleon Distance in Atomic Nuclei?
  • · Replies 17 ·
Replies
17
Views
3K
Undergrad Some confusion with the Binding Energy graph of atoms
  • · Replies 13 ·
Replies
13
Views
3K
Undergrad Binding energy, fusion and fission
  • · Replies 3 ·
Replies
3
Views
3K
High School Why don't neutrons bind into large out of control masses?
  • · Replies 28 ·
Replies
28
Views
3K
Undergrad Separation energy of nucleons and Coulomb barrier
  • · Replies 1 ·
Replies
1
Views
3K
Undergrad Q: Binding energy per nucleon & energy released in reaction
  • · Replies 2 ·
Replies
2
Views
10K
High School What causes mass defect in the nucleus?
  • · Replies 29 ·
Replies
29
Views
6K
Undergrad Question about gluons and nucleon binding
  • · Replies 5 ·
Replies
5
Views
2K
High School Nuclear Binding Energy: Is my understanding correct?
  • · Replies 1 ·
Replies
1
Views
2K