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It is shown that only a part of contributions in the full expression for the (amputated) two-leg graphs in effective single-scalar S-matrix theory can be considered as the self-energy function. This part is uniquely fixed by two requirements: the correct wave function normalization and the true (physical) position of the 2-leg Green function pole. On the one-loop level there is no need in fixing the other unknown constants because they turn out absorbed by the parameters that appear only in one-loop S-matrix graphs with n ≥ 3 legs. This means that the problem of fixing the dimensional coupling constants turns out shifted to the next stage of the renormalization procedure. Also, it is shown that the same is true with respect to the multi-component effective scalar theory. In this case the requirements of diagonalizability and correctness of pole positions turn out sufficient for one-loop renormalization of two-leg S-matrix graphs. [ABSTRACT FROM AUTHOR]

It is shown that only a part of contributions in the full expression for the (amputated) two-leg graphs in effective single-scalar S-matrix theory can be considered as the self-energy function. This part is uniquely fixed by two requirements: the correct wave function normalization and the true (physical) position of the 2-leg Green function pole. On the one-loop level there is no need in fixing the other unknown constants because they turn out absorbed by the parameters that appear only in one-loop S-matrix graphs with n ≽ 3 legs. This means that the problem of fixing the dimensional coupling constants turns out shifted to the next stage of the renormalization procedure. Also, it is shown that the same is true with respect to the multi-component effective scalar theory. In this case the requirements of diagonalizability and correctness of pole positions turn out sufficient for one-loop renormalization of two-leg S-matrix graphs. [ABSTRACT FROM AUTHOR]

We argue how it is possible to apply the general scheme of the effective scattering theory (EST) to the description of the hadronic processes. The results of the numerical tests of sum rules for πN spectrum parameters that follow from the bootstrap system allow us to claim the consistency of the predictions obtained in the framework of our approach with the known phenomenology. We also demonstrate that the tree-level low energy expansion coefficients computed in the framework of our approach show nice agreement with known experimental data. [ABSTRACT FROM AUTHOR]