Why protons/neutrons are not destroyed in nuclear reaction?

In summary, the strong nuclear force, mediated by gluons, holds quarks within a single nucleon together. However, the residual strong force, mediated by pions, is responsible for binding protons to neutrons. This force is described by an effective low-energy theory that breaks down at high energy and density. The phenomenon of color confinement, where quarks are never seen as isolated particles, is well-established but the theoretical reason for it is still not fully understood. Glueballs do not play a role in confinement, but could be included in low-energy theories.
  • #1
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In a nuclear reaction, protons and neutrons are separated from each other. My question is, why can protons and neutrons separate, but quarks can not separate from each other.

When the nucleus is intact, the gauge bosons for the strong nuclear force, gluons are responsible for holding quarks within a single proton or neutron together. They are also responsible for holding protons to neutrons.

So why do quarks within a particular proton (or neutron for that matter) get separated? Don't they "feel" the tearing force that is the sum of the protons repelling each other?

Does it have something to do with "glueballs" (don't laugh, but someone suggested this, hopefully they weren't messing with me) that don't apply between protons and neutrons.
 
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  • #2
Well, I'm not sure I entirely understand your question, but I have two clarifications to make. Yes, gluons hold single nucleon together, but no, they don't bind protons to neutrons. This occurs via the "residual strong force", which is mediated by pions, not gluons.

No, glueballs likely have nothing to do with the binding of nucleons, if they even exist.
 
  • #3
If you draw three parallel quark lines for a proton and three parallel quark lines for a neutron you can "exchange" two quarks between the nucleons; this exchange lines look somehow like a quark-antiquark pair, a pion.

The residual force is rather well-described by pion-exchange, but in principle other meson will contribute. The residual force is used in the context of an effective low energy theory that describes nucleon forces via the exchange of color-neutral objects. This effective theory breaks down at high energy and/or high density. E.g. in a quark gluon plasma the nucleons do break up and the effective low-energy theory is no longer valid.

The fact that quarks are never seen as isolated, colored objects (but appear only in color-neutral bound states) is called color-confinement. It is well-established in lattice gauge theory which allows one even to calculate nucleon masses, form factors etc. But the theoretical reason for color confinement is not completely understood. There are several approaches all showing some qualitative facts or hints indicating confinement, but a sound proof is still missing.

Glueballs do not play any role in confinement, but could be additional states to be taken into account in low-enery effective theories.
 

1. Why are protons and neutrons stable in nuclear reactions?

Protons and neutrons are stable in nuclear reactions due to the strong nuclear force, which is one of the four fundamental forces in nature. This force is responsible for holding together the nucleus of an atom, which is made up of protons and neutrons. This force is much stronger than the repulsive force between positively charged protons, which keeps the nucleus stable and prevents protons and neutrons from being destroyed.

2. How do protons and neutrons resist destruction in nuclear reactions?

Protons and neutrons resist destruction in nuclear reactions due to their intrinsic properties. Protons have a positive charge and are made up of three quarks, while neutrons have no charge and are also made up of three quarks. These properties make them resistant to destruction, as they are held together by the strong nuclear force.

3. Can protons and neutrons be destroyed in nuclear reactions?

In nuclear reactions, protons and neutrons can be transformed into other particles, such as alpha particles or beta particles. However, they are not destroyed in the sense that their mass and energy are conserved. The total number of protons and neutrons before and after a nuclear reaction remains the same, but their arrangement may change.

4. What role do protons and neutrons play in nuclear reactions?

Protons and neutrons play a crucial role in nuclear reactions as they make up the nucleus of an atom. During a nuclear reaction, the nuclei of atoms collide, and protons and neutrons may be exchanged or transformed. This results in the release of energy and the formation of new elements.

5. Are protons and neutrons destroyed in nuclear fission reactions?

In nuclear fission reactions, the nucleus of an atom is split into smaller fragments. While protons and neutrons may be released during this process, they are not destroyed. The number of protons and neutrons before and after the reaction remains the same, but their arrangement changes. This process is possible due to the strong nuclear force holding the nucleus together and the release of energy from the reaction.

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