4.5. STRONG INTERACTION POTENTIALS 229
while in the nucleon level,
(4.5.55) nucleon strong force is repulsive in 0<r< 10 −^13 cm.
The conflicting characteristics of the strong interactionsdemonstrated in (4.5.54) and (4.5.55)
can hardly be explained by any existing theory. However, thelayered strong interaction po-
tentials in (4.5.41) derived based on PID and PRI lead to a natural explanation ofthese charac-
teristics, as well as explanation of the quark confinement and asymptotic freedom in previous
subsections. In this subsection, we shall show that the strong interaction nucleon potential
(4.5.38), which can be regarded as a modified Yukawa potential, fits experiments. Mean-
while, we also determine some parameters for the strong interaction potentials, including the
strong chargegs.
- Experimental results. Experiments showed that the strong nucleon force has the
following properties:
- Nucleon force is of short-ranged, with the radius of the force range:r∼ 2 × 10 −^13 cm.
- Nucleon force has a repelling center and an attracting region: it is repulsive forr<
1
2 ×^10
− (^13) cm, is attractive for 1
2 ×^10
− (^13) <r< 2 × 10 − (^13) cm, and diminishes forr>
2 × 10 −^13. Namely, experimentally, the nucleon force behaves as
(4.5.56) Fexp
>0 for 0<r<r=1
2
× 10 −^13 cm,<0 forr<r< 2 × 10 −^13 cm,
⋍0 forr> 2 × 10 −^13 cm.More precisely, the experimental data for the strong interaction nucleon potential can
be schematically shown in Figure4.2; see (Weisskopf, 1972 ).01020-10-2012 1 2 r(10− (^13) cm)
Figure 4.2: Experimental curve of nucleon potential energy.
- Yukawa potential. Based on the classical strong interaction theory, the potential
holding nucleons to form an atomic nucleus is the Yukawa potential
(4.5.57) ΦY=−
g
r
e−knr, r 1 =1
kn
= 10 −^13 cm,