[Richard777 (OP)]

An interaction between two particles is assumed to be mediated by an “exchange” of bosons. A force may be associated with each boson and with each particle.

Force may be represented as a vector. The interaction may be represented as a four vector set. The four vectors may be arranged as two pairs of vectors, each pair represents forces associated with a particle and a “corresponding boson”.

An interaction of special interest is between an electron and a photon as represented by the Compton equation, published in 1923. Energy is transferred from the photon to the electron. The collision is elastic and each particle recoils in a different direction. Vector components will give the Compton equation.

See attachment for vector definition.