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Effects of nonlocal one-pion-exchange potential in deuteron

Description: The off-shell aspects of the one-pion-exchange potential (OPEP) are discussed. Relativistic Hamiltonians containing relativistic kinetic energy, relativistic OPEP with various off-shell behaviors and Argonne v{sub 18} short-range parameterization are used to study the deuteron properties. The OPEP off-shell behaviors depend on whether a pseudovector or pseudoscalar pion-nucleon coupling is used and are characterized by a parameter {mu}. The authors study potentials having {mu} = {minus}1, 0 and +1 and they find that they are nearly unitarily equivalent. They also find that a nonrelativistic Hamiltonian containing local potentials and nonrelativistic kinetic energy provides a good approximation to a Hamiltonian containing a relativistic OPEP based on pseudovector pion-nucleon coupling and relativistic kinetic energy.
Date: May 28, 1999
Creator: Forest, J.L.
Partner: UNT Libraries Government Documents Department

Quantum Monte Carlo studies of relativistic effects in light nuclei

Description: Relativistic Hamiltonians are defined as the sum of relativistic one-body kinetic energy, two- and three-body potentials and their boost corrections. In this work the authors use the variational Monte Carlo method to study two kinds of relativistic effects in the binding energy of {sup 3}H and {sup 4}He. The first is due to the nonlocalities in the relativistic kinetic energy and relativistic one-pion exchange potential (OPEP), and the second is from boost interaction. The OPEP contribution is reduced by about 15% by the relativistic nonlocality, which may also have significant effects on pion exchange currents. However, almost all of this reduction is canceled by changes in the kinetic energy and other interaction terms, and the total effect of the nonlocalities on the binding energy is very small. The boost interactions, on the other hand, give repulsive contributions of 0.4 (1.9) MeV in {sup 3}H ({sup 4}He) and account for 37% of the phenomenological part of the three-nucleon interaction needed in the nonrelativistic Hamiltonians.
Date: May 1, 1998
Creator: Forest, J. L.; Pandharipande, V. R. & Arriaga, A.
Partner: UNT Libraries Government Documents Department

Variational Monte Carlo Calculations of {sup 3}He and {sup 4}He with a Relativistic Hamiltonian - II

Description: In relativistic Hamiltonians the two-nucleon interaction is expressed as a sum of {tilde v}{sub ij}, the interaction in the P{sub ij}=0 rest frame, and the ''boost interaction'' {delta}v(P{sub ij}) which depends upon the total momentum P{sub ij} and vanishes in the rest frame. The {delta}v can be regarded as a sum of four terms: {delta}v{sub RE}, {delta}v{sub LC}, {delta}v{sub TP} and {delta}v{sub QM}; the first three originate from the relativistic energy-momentum relation, Lorentz contraction and Thomas precession, while the last is purely quantum. The contributions of {delta}v{sub RE} and {delta}v{sub LC} have been previously calculated with the variational Monte Carlo method for {sup 3}H and {sup 4}He. In this brief note we report the results of similar calculations for the contributions of {delta}v{sub TP} and {delta}v{sub QM}. These are found to be rather small.
Date: October 1, 1994
Creator: Forest, J.L.; Pandharipande, V.R.; Carlson, J. & Schiavilla, R.
Partner: UNT Libraries Government Documents Department