The Experts below are selected from a list of 258 Experts worldwide ranked by ideXlab platform
S. Fantoni - One of the best experts on this subject based on the ideXlab platform.
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Auxiliary field diffusion Monte Carlo calculation of ground state properties of neutron drops
Nuclear Physics, 2004Co-Authors: F. Pederiva, A. Sarsa, Kevin Schmidt, S. FantoniAbstract:Abstract The auxiliary field diffusion Monte Carlo method has been applied to simulate droplets of 7 and 8 neutrons. Results for realistic nucleon–nucleon Interactions, which include tensor, spin–orbit and three-body forces, plus a standard one-body confining potential, have been compared with analogous calculations obtained with Green's function Monte Carlo methods. We have studied the dependence of the binding energy, the one-body density and the spin–orbit splittings of 7 n on the depth of the confining potential. The results obtained show an overall agreement between the two quantum Monte Carlo methods, although there persist differences in the evaluation of spin–orbit forces, as previously indicated by bulk neutron matter calculations. Energy density functional models, largely used in astrophysical applications, seem to provide results significantly different from those of quantum simulations. Given its scaling behavior in the number of nucleons, the auxiliary field diffusion Monte Carlo method seems to be one of the best candidate to perform ab initio calculations on neutron rich nuclei.
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Auxiliary field diffusion Monte Carlo calculation of ground state properties of neutron drops
Nuclear Physics A, 2004Co-Authors: F. Pederiva, A. Sarsa, K.e. Schmidt, S. FantoniAbstract:The Auxiliary Field Diffusion Monte Carlo method has been applied to simulate droplets of 7 and 8 neutrons. Results for realistic Nucleon-Nucleon Interactions, which include tensor, spin--orbit and three--body forces, plus a standard one--body confining potential, have been compared with analogous calculations obtained with Green's Function Monte Carlo methods. We have studied the dependence of the binding energy, the one--body density and the spin--orbit splittings of $^7n$ on the depth of the confining potential. The results obtained show an overall agreement between the two quantum Monte Carlo methods, although there persist differences in the evaluation of spin--orbit forces, as previously indicated by bulk neutron matter calculations. Energy density functional models, largely used in astrophysical applications, seem to provide results significantly different from those of quantum simulations. Given its scaling behavior in the number of nucleons, the Auxiliary Field Diffusion Monte Carlo method seems to be one of the best candidate to perform {\sl ab initio} calculations on neutron rich nuclei.Comment: 8 pages, 3 figure
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spin susceptibility of neutron matter at zero temperature
Physical Review Letters, 2001Co-Authors: S. Fantoni, A Sarsa, Kevin SchmidtAbstract:The Auxiliary Field Diffusion Monte Carlo method is applied to compute the spin susceptibility and the compressibility of neutron matter at zero temperature. Results are given for realistic Interactions which include both a two-body potential of the Argonne type and the Urbana IX three-body potential. Simulations have been carried out for about 60 neutrons. We find an overall reduction of the spin susceptibilty by about a factor 3 with respect to the Pauli susceptibility for a wide range of densities. Results for the compressibility of neutron matter are also presented and compared with other available estimates obtained for semirealistic Nucleon-Nucleon Interactions by using other techniques.
T.t.s. Kuo - One of the best experts on this subject based on the ideXlab platform.
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Nuclear Shell Model Calculations with Fundamental Nucleon-Nucleon Interactions
Physics Reports, 1996Co-Authors: X. W. Pan, T.t.s. Kuo, M. Vallieres, D. H. FengAbstract:Some fundamental Nucleon-Nucleon Interactions and their applications to finite nuclei are reviewed. Results for the few-body systems and from Shell-Model calculations are discussed and compared to point out the advantages and disadvantages of the different Nucleon-Nucleon Interactions. The recently developed Drexel University Shell Model (DUSM) code is mentioned.
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Model-space-size dependence of nuclear matter model-space Brueckner-Hartree-Fock calculations.
Physical Review C, 1991Co-Authors: H. Q. Song, T.t.s. KuoAbstract:The effect of model-space size on the model-space Brueckner-Hartree-Fock (MBHF) results of the nuclear matter saturation property is discussed with the Reid soft-core and Paris Nucleon-Nucleon Interactions. A prescription for optimal choice of the model-space size in the nuclear matter MBHF calculation is suggested.
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Linked diagram expansions for the nuclear transition matrix and the normalization of model-space wave functions
Nuclear Physics A, 1991Co-Authors: D.b. Stout, T.t.s. KuoAbstract:Abstract A unified and relatively simple linked-diagram expansion for performing microscopic calculations of the nuclear transition matrix T fi is derived. We first review a folded-diagram effective interaction theory, based on which, the model-space effective hamiltonian can be calculated from realistic Nucleon-Nucleon Interactions. An important ingredient of this theory is the wave-function decomposition theorem which provides a convenient connection between the true and model-space wave functions. By directly making use of this theorem, a folded-diagram expansion of T fi is readily obtained. Using a partial summation method, the folded diagrams of T fi are then eliminated, leading to a considerably simpler expression for T fi . Our formalism requires that T fi must be calculated in strict consistence with the derivation of the model-space effective hamiltonian H eff . The model-space wave function normalization factor contained in our T fi , may play an important role in “quenching” the calculated nuclear transition matrix. A simple method for evaluating this normalization factor is derived, namely it can be obtained readily from the energy derivative of the respective self-consistent eigenvalue of H eff .
Li-sheng Geng - One of the best experts on this subject based on the ideXlab platform.
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Pion-mass dependence of the Nucleon-Nucleon interaction
Physics Letters B, 2020Co-Authors: Qian-qian Bai, Chun-xuan Wang, Yang Xiao, Li-sheng GengAbstract:Abstract Nucleon-Nucleon Interactions, both bare and effective, play an important role in our understanding of the non-perturbative strong interaction, as well as nuclear structure and reactions. In recent years, tremendous efforts have been seen in the lattice QCD community to derive Nucleon-Nucleon Interactions from first principles. Because of the daunting computing resources needed, most of such simulations were still performed with larger than physical light quark masses. In the present work, employing the recently proposed covariant chiral effective field theory (ChEFT), we study the light quark mass dependence of the Nucleon-Nucleon interaction extracted by the HALQCD group. It is shown that the pion-full version of the ChEFT can describe the lattice QCD data with m π = 469 MeV and their experimental counterpart reasonably well, while the pion-less version can describe the lattice QCD data with m π = 672 , 837 , 1015 , 1171 MeV, for both the S 0 1 and S 1 3 - D 1 3 channels. The slightly better description of the single channel than the triplet channel indicates that higher order studies are necessary for the latter. Our results confirmed previous studies that the Nucleon-Nucleon interaction becomes more attractive for both the singlet and triplet channels as the pion mass decreases towards its physical value. It is shown that the virtual bound state in the S 0 1 channel remains virtual down to the chiral limit, while the deuteron only appears for a pion mass smaller than about 400 MeV. It seems that proper chiral extrapolations of Nucleon-Nucleon interaction are possible for pion masses smaller than 500 MeV, similar to the mesonic and one-baryon sectors.
D.o. Riska - One of the best experts on this subject based on the ideXlab platform.
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The reaction pp→ppη and the eta–nucleon and nucleon–nucleon Interactions
Nuclear Physics A, 2001Co-Authors: M. T. Peña, H. Garcilazo, D.o. RiskaAbstract:Abstract The π , η and ρ exchange contributions to the cross section for the reaction pp→ppη near threshold are calculated, with a phenomenological description of the intermediate S11 (N(1535)) resonance for all exchange mechanisms. The final state interaction in the pp system is described by realistic nucleon–nucleon interaction models. The sensitivity of the results to the phenomenological models for the η –nucleon transition amplitude and the nucleon–nucleon interaction is explored. The η -exchange mechanism is found to play a dominant role. The off-shell behavior of the ηN→ηN amplitude within the η exchange amplitude leads to a result significantly different from that obtained with the constant scattering length approximation. The two-nucleon amplitudes that are associated with the short-range components of the nucleon–nucleon interaction contribute significantly to the cross section.
Qian-qian Bai - One of the best experts on this subject based on the ideXlab platform.
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Pion-mass dependence of the Nucleon-Nucleon interaction
Physics Letters B, 2020Co-Authors: Qian-qian Bai, Chun-xuan Wang, Yang Xiao, Li-sheng GengAbstract:Abstract Nucleon-Nucleon Interactions, both bare and effective, play an important role in our understanding of the non-perturbative strong interaction, as well as nuclear structure and reactions. In recent years, tremendous efforts have been seen in the lattice QCD community to derive Nucleon-Nucleon Interactions from first principles. Because of the daunting computing resources needed, most of such simulations were still performed with larger than physical light quark masses. In the present work, employing the recently proposed covariant chiral effective field theory (ChEFT), we study the light quark mass dependence of the Nucleon-Nucleon interaction extracted by the HALQCD group. It is shown that the pion-full version of the ChEFT can describe the lattice QCD data with m π = 469 MeV and their experimental counterpart reasonably well, while the pion-less version can describe the lattice QCD data with m π = 672 , 837 , 1015 , 1171 MeV, for both the S 0 1 and S 1 3 - D 1 3 channels. The slightly better description of the single channel than the triplet channel indicates that higher order studies are necessary for the latter. Our results confirmed previous studies that the Nucleon-Nucleon interaction becomes more attractive for both the singlet and triplet channels as the pion mass decreases towards its physical value. It is shown that the virtual bound state in the S 0 1 channel remains virtual down to the chiral limit, while the deuteron only appears for a pion mass smaller than about 400 MeV. It seems that proper chiral extrapolations of Nucleon-Nucleon interaction are possible for pion masses smaller than 500 MeV, similar to the mesonic and one-baryon sectors.
