ABSTRACT
In the language of quantum field theory, force field influence on a particle is interpreted as emission and absorption of the quanta of this field. For example, the electromagnetic interaction between two electrons appears due to photons exchange. Photon masslessness reveals itself in the long-range action of the Coulomb forces, that is, the Coulomb potential decreases with a distance as 1/r. It is natural to expect that the massive carrier of an interaction will produce a short-range potential. In an analogy with the exchange nature of electromagnetic forces, in 1935 H. Yukawa [23] introduced a hypothesis about massive quantum exchange, between nucleons in a nucleus. The idea was, that the interaction between this massive quantum (pi-meson) and nucleon N appears as a result of combination of virtual process
N ↔ N ′ + pi. (9.1) In other words, the Hamiltonian, causing the interaction between nucleons in a nucleus Hint must be of the form:
Hint ∼ N(x)N(x)pi(x). (9.2) Connections of this kind often occur in elementary particle physics and they are called Yukawa couplings.
