- #1
fermi
- 76
- 5
What particle mediates the nuclear forces amongst the protons and neutrons inside nuclei? Yukawa thought it was the pions that mediated the nuclear force, but I am yet to see a good theory (or even a model) that can explain nuclear binding quantitatively.
Before you answer, a clarification is in order: I am not asking about the strong forces that confine the quarks and make hadrons. That's QCD physics with quarks and gluons. However, inside nuclei the protons and neutrons do not dissolve into a quark and gluon soup. They remain as protons and neutrons. Specifically, they remain as color-singlet objects. This is not unexpected, since the nuclear binding energy (per nucleon) is at least two orders of magnitude smaller than the QCD binding energy, or the mass of the nucleons. (The highest nuclear binding energy per nucleon is only 8.9 Mev for some Iron isotopes.)
So what is the modern prevailing view on the mediator of nuclear forces? Pions still? Or other mesons? Or even multiple gluon exchanges? It would be very difficult to get flavor (isospin) dependent forces by gluon exchanges, which nuclear forces seem to be. (The attraction in between two neutrons (or two protons) is a lot weaker than the attraction between a proton and neutron.)
Before you answer, a clarification is in order: I am not asking about the strong forces that confine the quarks and make hadrons. That's QCD physics with quarks and gluons. However, inside nuclei the protons and neutrons do not dissolve into a quark and gluon soup. They remain as protons and neutrons. Specifically, they remain as color-singlet objects. This is not unexpected, since the nuclear binding energy (per nucleon) is at least two orders of magnitude smaller than the QCD binding energy, or the mass of the nucleons. (The highest nuclear binding energy per nucleon is only 8.9 Mev for some Iron isotopes.)
So what is the modern prevailing view on the mediator of nuclear forces? Pions still? Or other mesons? Or even multiple gluon exchanges? It would be very difficult to get flavor (isospin) dependent forces by gluon exchanges, which nuclear forces seem to be. (The attraction in between two neutrons (or two protons) is a lot weaker than the attraction between a proton and neutron.)