# A Construction of an Effective Hamiltonian from Feynman Diagrams: Application to the Light-Front Yukawa Model

Progress of Theoretical Physics, Jul 2001

We study a similarity transformation to construct an effective Hamiltonian systematically, which does not contain particle-number-changing interactions, by means of the Fukuda-Sawada-Taketani-Okubo method. We show that such a Hamiltonian can be constructed from Feynman diagrams and give rules for constructing it in the light-front Yukawa model. We prove that it is renormalized by the familiar covariant perturbative renormalization procedure. It is very advantageous that the effective Hamiltonian can be obtained from our rules immediately. We also numerically diagonalize it to second order in the coupling constant as an exercise.

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Yuki Yamamoto. A Construction of an Effective Hamiltonian from Feynman Diagrams: Application to the Light-Front Yukawa Model, Progress of Theoretical Physics, 2001, 99-130, DOI: 10.1143/PTP.106.99