Low-Energy Equivalent-Potential Approach for Strong Interactions

Equations are given for constructing an equivalent potential at each energy from the crossed-channel absorptive part. These are straightforward generalizations of the Charap-Fubini formulas. The absorptive part can be calculated with the help of the strip approximation. If we solve our equations by iteration, we can get the potential more and more accurately at smaller distances. The first approximation consists of an appropriate number of crossed-channel partial waves which can be calculated by solving a Schrödinger equation with an equivalent potential as input. The approach is applied in lowest order to calculate the parameters of the $\rho$ and $\varphi$ mesons.