# Strong force as exchange of mesons, or of quark and antiquark

• I
• crick
In summary, the strong force between nucleons can be described as the exchange of a meson or the exchange of a quark and an antiquark. However, there is some inconsistency between the two interpretations as to which nucleon gives or receives the meson. Additionally, there is a time axis in Feynman diagrams but it only represents the initial and final states, not the actual time ordering of events.
crick
The (residual) strong force between nucleons can be desribed as

- The exchange of a meson (from a nucleon to the other), as in picture b)
- The exchange of a quark and an antiquark: in picture a) one nucleon "gives" a quark and receive an antiquark and it's the opposite for the other

I do no see how these two description are consistent with each other since in picture b) the meson (a quark + an antiquark) goes from one nucleon to the other, while in a) there is an exchange. So are these two interpretation equivalent? The nucleon that gives the quark also gives the antiquark (and therefore a meson) or receives it instead?

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Same thing. You don't have an actual time axis anyway in these diagrams, only initial and final states.

Here is your meson going from left to right in the left diagram:

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crick
mfb said:
Same thing. You don't have an actual time axis anyway in these diagrams, only initial and final states.

Here is your meson going from left to right in the left diagram:

View attachment 227384

Thanks for the answer.

But there is actually a time axis and it is vertical (going from down to up). I'm aware that antiparticles move backwards in time (in the picture it moves downward a bit) but the fact is that it moves from left to right "in space".

Is this wrong? So actually (besides moving backwards in time) the direction in space indicated by the arrow in the feynman diagram should be reversed for an antiparticle?

crick said:
I'm aware that antiparticles move backwards in time

No they don't.

Klystron
crick said:
But there is actually a time axis and it is vertical (going from down to up).
The only meaningful times in a Feynman diagram are the initial and final states. Everything inside doesn't have a time ordering, and in fact you have to consider all times for all vertices for calculating such a diagram.

## 1. What is the strong force?

The strong force is one of the four fundamental forces in physics, along with gravity, electromagnetism, and the weak force. It is responsible for holding together the nucleus of an atom by binding protons and neutrons together.

## 2. How is the strong force transmitted?

The strong force is transmitted through the exchange of particles called mesons. These particles are made up of quarks and antiquarks, which are the building blocks of protons and neutrons.

## 3. What is the role of quarks in the strong force?

Quarks are the fundamental particles that make up protons and neutrons. They are also responsible for carrying the strong force between these particles through the exchange of gluons, which are the carriers of the strong force.

## 4. How does the strong force differ from the other fundamental forces?

The strong force is different from the other fundamental forces because it only acts on particles that contain quarks, such as protons and neutrons. It is also the strongest of the four fundamental forces, but it has a very short range, only acting within the nucleus of an atom.

## 5. Can the strong force be observed in everyday life?

No, the strong force is not observable in everyday life because it only acts at a very small scale within the nucleus of an atom. However, its effects can be seen in the stability of matter and the energy released in nuclear reactions.

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