Theory of Many-Fermion System on Unitary-Transformation Method

Right-unitary transformation theory and applications.

We develop a new transformation theory in quantum physics, where the transformation operators, defined in the infinite dimensional Hilbert space, have right-unitary inverses only. Through several theorems, we discuss the properties of state space of such operators. As one application of the right-unitary transformation (RUT), we show that using the RUT method, we can solve exactly various inter...

Two-pion exchange electromagnetic current in chiral effective field theory using the method of unitary transformation

Chiral effective field theory (EFT) provides a systematic and model-independent framework to analyze low-energy hadronic processes in harmony with the spontaneously broken approximate chiral symmetry of QCD. This approach has been successfully applied to the derivation of the nuclear forces and, more recently, also hyperon-nucleon and hyperon-hyperon interactions, see Refs. [1, 2, 3] for review...

Rayleigh-Schrödinger-Goldstone variational perturbation theory for many fermion systems

We present a Rayleigh-Schrödinger-Goldstone perturbation formalism for many fermion systems. Based on this formalism, variational perturbation scheme which goes beyond the Gaussian approximation is developed. In order to go beyond the Gaussian approximation, we identify a parent Hamiltonian which has an effective Gaussian vacuum as a variational solution and carry out further perturbation with ...

A unitary transformation method for angle-of-arrival estimation

New Numerical Method for Fermion Field Theory

A new deterministic, numerical method to solve fermion field theories is presented. This approach is based on finding solutions Z[J ] to the lattice functional equations for field theories in the presence of an external source J . Using Grassmann polynomial expansions for the generating functional Z, we calculate propagators for systems of interacting fermions. These calculations are straightfo...