[Physics] Electromagnetic force between neutron and proton

electrostaticsnuclear-physics

In a nucleus, two protons exert an electromagnetic force on each other and if they are able to break the electrostatic repulsion barrier they exert nuclear force on each other. I know that neutrons are effective in binding the nucleus as they effectively break the electrostatic barrier as they have no charge and thus are easily able to exert a force on the protons to bring them together.Is the electromagnetic attractive force between the neutron and proton also a contributing factor?Does a neutron exert electromagnetic force on a proton as well or only nuclear force,in an atom?

Best Answer

The quarks within a nucleon, proton or neutron, are charged, but the ones in the neutron add up to over all charge 0.

neutron

The nucleons though are complicated because of the strong interaction which has a sea of quarks antiquarks and gluons within the nucleon bag, so there will be a charge distribution within the neutron which in some models is calculated to be negative in the center ( so positive on the ouside), so it would be a repulsive force with the proton charges.

What saves the day is the magnitude of the coupling constants. The strong QCD force is of order 1, the electromagnetic of order 1/137 and the multiple vertices in the inevitable many body problem Feynman diagrams will reduce the effect by orders of magnitude.

The spin effects will be more visible, in the way the protons and neutrons are organized within a nucleus, and has to be taken into account in the nuclear models, individual magnetic moments adding up to the magnetic moment of a nucleus.