Spin-Spin interaction question

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In summary, diprotons are not stable due to spin-spin interactions and the Pauli exclusion principle, which cause the two protons to have anti-aligned spins and a negative binding energy. This is because in proton-proton and neutron-neutron interactions, the isospins are identical and there is only one possible spin arrangement that results in a slightly non-bound state. In contrast, in proton-neutron interactions, the two particles are not identical and can have different spin orientations, resulting in a bound state such as the deuteron. While there is a slight attractive potential for same-spin proton-proton and neutron-neutron interactions, it is not strong enough to form a bound state, unlike in one-dimensional systems where every attractive potential has at least
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DaveSmith
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According to wikipedia
http://en.wikipedia.org/wiki/Diproton
"Diprotons are not stable; this is due to spin-spin interactions in the nuclear force, and the Pauli exclusion principle, which forces the two protons to have anti-aligned spins and gives the diproton a negative binding energy."

But spin in proton and neutron is also the same (spin=1⁄2, isospin=1⁄2), and a proton and neutron stick together so why can't p-p or n-n can stick together?
 
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In pp and nn isospins are identical, therefore (due to the Pauli principle for identical particles) you only have one arrangement for spin (which results in a slightly non-bound pp or nn) whereas for np the two particles are not identical and there is no restriction for the spin (which results in an slightly unbound np which we do not consider and a bound np = the deuteron).

For nn and pp the total interaction potential (it is not a simple potential like exp(-r/a)/r but something more complicated) for the required spin and isospin orientation is slightly attractive (which can be seen in the partial wave analysis of pp and nn scattering) but not attractive enough to form a bound state. Perhaps you remember from QM that in dim=1 every attractive potential has at least one bound state but in dim=3 this need not be the case.
 

1. What is spin-spin interaction?

Spin-spin interaction is a phenomenon in quantum mechanics where the spins of particles interact with each other, affecting their behavior and energy levels.

2. How does spin-spin interaction occur?

Spin-spin interaction can occur through electromagnetic forces or through the exchange of virtual particles between particles with spin.

3. What are the consequences of spin-spin interaction?

The consequences of spin-spin interaction include splitting energy levels, shifting the energy levels of particles, and affecting the behavior of particles in magnetic fields.

4. Can spin-spin interaction be observed in everyday life?

Yes, spin-spin interaction can be observed in everyday life through phenomena such as nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI).

5. How is spin-spin interaction related to spin-spin coupling?

Spin-spin coupling is a type of spin-spin interaction where the spins of particles are coupled together, leading to splitting of energy levels and affecting the behavior of particles.

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