# Pion-Meson production during nuclear force

I was learning about quantum chromodynamics and how the force that holds particles in the nucleus works. I learned a pion-meson is created during gluon interaction within the particle and that meson travels to the other particle and creates more gluons. I was wondering what inhibits the pion-meson creation?

I will quote from this site, in order to clarify the difference between the strong force, called the nuclear force, and quantum chromodynamics:

A force which can hold a nucleus together against the enormous forces of repulsion of the protons is strong indeed. However, it is not an inverse square force like the electromagnetic force and it has a very short range. Yukawa modeled the strong force as an exchange force in which the exchange particles are pions and other heavier particles. The range of a particle exchange force is limited by the uncertainty principle. It is the strongest of the four fundamental forces

Since the protons and neutrons which make up the nucleus are themselves considered to be made up of quarks, and the quarks are considered to be held together by the color force, the strong force between nucleons may be considered to be a residual color force. In the standard model, therefore, the basic exchange particle is the gluon which mediates the forces between quarks. Since the individual gluons and quarks are contained within the proton or neutron, the masses attributed to them cannot be used in the range relationship to predict the range of the force. When something is viewed as emerging from a proton or neutron, then it must be at least a quark-antiquark pair, so it is then plausible that the pion as the lightest meson should serve as a predictor of the maximum range of the strong force between nucleons

italics mine

The sketch is an attempt to show one of many forms the gluon interaction between nucleons could take, this one involving up-antiup pair production and annililation and producing a π- bridging the nucleons.

We don't currently have the technology to even see the nucleus of an atom. There are many speculations but the most probably answer is that as the quarks making up the protons and neutrons interact strong force waves are released (gluons). A pion does bounce back and fourth between the protons and neutrons. Both are attracted to the pion and the gluons probably are responsible for holding the pion in place. Scientists really don't know the answer that well. The gluons also hold the quarks together.

Electromagnetism is going to repulse the protons and neutrons but the most protons and neutrons will ever be apart is two femtometers. At this short distance strong nuclear force (the attraction to the meson bouncing back and fourth between them) pulls them together.

So in conclusion - the pion, made of a quark and anti-quark is constantly being created and destroyed. Its creation is PROBABLY inhibited by the changing of quark colors but there is no real answer (right now). We don't even know what quarks are made of! Hope this made things clearer.

• "We don't currently have the technology to even see the nucleus of an atom." Is only correct if you limit your probes to light or your tools to to simple ones. We've been look at the nuclei of atoms for more than 100 years, though admittedly the first fifty didn't produce much by way of resolution. – dmckee Aug 20 '16 at 23:36