Pion Range of Strong Force
An estimate of the range of the strong force can be made by assuming that it is an exchange force involving neutral pions. When the range expression
is used with a pion mass of
p0 mass = 264 me = 135.0 MeV/c2
the range obtained is
Range = 0.73 x 10-15 m = 0.61 x classical proton radius.
This range is in the neighborhood of one fermi. When Hideki Yukawa was working of a theory of the strong force, he judged that the range of the nuclear force was about a fermi, and calculated that the exchange particle should be in the neighborhood of 100 MeV in mass equivalent. This triggered the search which led to the discovery of the pion. When the nuclear particles are very close together, other heavier particles must also be included in this type of model of the strong force. The current view is that the strong force is fundamentally an interaction between quarks, and that the strong force is really a residual color force.
Fundamental force concepts