Reference state quantum field theory

In 1974 Walecka [Wa 74] introduced the first relativistic quantum field theory for nuclear matter. The mesonic degrees of freedom included scalar and vector fields. This model, referred to as the quantum hadrodynamic (QHD) model, accounts for spin-orbit splitting in the shell model and the ground state properties of many nuclei [Se 85]. Noble [No 79] demonstrated the consistency between the strengths of the scalar and vector potentisds in Walecka s QHD theory and those obtained from relativistic one-meson exchange potentials for the free NN interaction. 

The reference state of A-electron theory becomes a reference vacuum state 4>) in the field theory. A complete orthonormal set of spin-indexed orbital functions fip(x) is defined by eigenfunctions of a one-electron Hamiltonian Ti, with eigenvalues ep. The reference vacuum state corresponds to the ground state of a noninteracting A-electron system determined by this Hamiltonian. N occupied orbital functions (el < pi) are characterized by fermion creation operators a such that a] ) =0. Here pt is the chemical potential or Fermi level. A complementary orthogonal set of unoccupied orbital functions are characterized by destruction operators aa such that aa < >) = 0 for ea > p and a > N. A fermion quantum field is defined in this orbital basis by... 

In this chapter we present an analysis of recent advances in quantum and semiclasslcal theory concerned with the prediction of energy distributions of fragments formed by singlephoton photodissociation. Advances in experimental technique have resulted in significant progress in this field see Jackson and Okabe, this volume, and references (5-7). Hence, a theoretical state-to-state description of polyatomic photodissociation is of considerable interest. 

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