AV18 Potential Research Articles

LOCV approach and core-crust transition in neutron stars

In this paper, we have calculated the core-crust transition parameters and the location of inner edge for crust in the neutron stars. We have also investigated the structural properties of neutron stars, such as mass and radius for the core and crust, the moment of inertia, and its crustal fraction. Here we have employed the lowest-order constrained variational approach and used the UV14 + TNI and AV18 potentials to compute the equation of state of nuclear matter. Finally, we have compared our results with those of other techniques.

Break-up channels in muon capture onHe3

The mu + 2H -> nu + n + n, mu + 3He -> nu + 3H, mu + 3He -> nu + n + d and mu + 3He -> nu + n + n + p capture reactions are studied with various realistic potentials under full inclusion of final state interactions. Our results for the two- and three-body break-up of 3He are calculated with a variety of nucleon-nucleon potentials, among which is the AV18 potential, augmented by the Urbana~IX three-nucleon potential. Most of our results are based on the single nucleon weak current operator. As a first step, we have tested our calculation in the case of the mu + 2H -> nu + n + n and mu + 3He -> nu + 3H reactions, for which theoretical predictions obtained in a comparable framework are available. Additionally, we have been able to obtain for the first time a realistic estimate for the total rates of the muon capture reactions on 3He in the break-up channels: 544 1/s and 154 1/s for the n + d and n + n + p channels, respectively. Our results have also been compared with the most recent experimental data, finding a rough agreement for the total capture rates, but failing to reproduce the differential capture rates.

Nonsymmetrized Hyperspherical Harmonics with Realistic Potentials

The Schrodinger equation is solved for an A-nucleon system using an expansion of the wave function in nonsymmetrized hyperspherical harmonics. Our approach is based on the formalism developed by Gattobigio et al. (Phys Rev A 79:032513, 2009; Few-Body Syst 45:127, 2009; Phys Rev C 83:024001, 2011), where it was applied to four- and six-body systems using central and central spin dependent potentials. In addition we include isospin dependence and noncentral forces in order to be able to make calculations also with more realistic NN potential models. Furthermore, a more efficient procedure to determine the fermionic spectrum is used. The approach is applied to four- and six-body nuclei (4He,6Li) with various NN potential models including for 4He the realistic AV18 potential. It is shown that the results for ground-state energy and radius agree well with those from the literature.

Equation of State for Neutron Star Matter with the Lowest Order Constrained Variational Method and Kaon Condensation

We investigate the equation of state of kaon condensed neutron star matter using the lowest order constrained variational (LOCV) method. In this paper, we employ the AV18 and AV14 potentials for nucleon-nucleon interaction and use the chiral model for kaon-nucleon interaction. According to our results, the kaon condensation occurs at some density values and softens the equation of state as other techniques have shown.

LOCV CALCULATION OF DENSITY DEPENDENCE OF NUCLEAR SYMMETRY ENERGY AT DIFFERENT SPIN STATES

In this paper, we use the lowest order constrained variational method to study the behavior of nuclear symmetry energy versus density and spin states of neutrons and protons with AV18 potential. The dependency of incompressibility at saturation density on isospin asymmetry, ferromagnetic spin states and antiferromagnetic spin states is also investigated.

Nonsymmetrized Hyperspherical Harmonics with Realistic NN Potentials

The Schrödinger equation is solved for an A-nucleon system using an expansion of the wave function in nonsymmetrized hyperspherical harmonics. Our approach is based on the formalism developed by Gattobigio et al. (Phys Rev A 79:032513, 2009; Few-Body Syst 45:127, 2009; Phys Rev C 83:024001, 2011), where it was applied to four- and six-body systems using central and central spin dependent potentials. In addition we include isospin dependence and noncentral forces in order to be able to make calculations also with more realistic NN potential models. Furthermore, a more efficient procedure to determine the fermionic spectrum is used. The approach is applied to four- and six-body nuclei (4He,6Li) with various NN potential models including for 4He the realistic AV18 potential. It is shown that the results for ground-state energy and radius agree well with those from the literature.

Few-nucleon systems interacting via non-local quark-model baryon-baryon interaction

Low- and medium-energy nucleon-deuteron scattering less than the incident energy 65 MeV per nucleon is examined by using the quark-model nucleon-nucleon interaction fss2. The off-shell effect of this non-local interaction yields a part of the attractive effect given by the three-nucleon force in the standard description by meson-exchange potentials. The triton binding energy and the spin-doublet scattering length are well described by fss2 without introducing the three-nucleon force. The nucleon analyzing power is slightly improved from the results by the AV18 potential, but the so-called Ay puzzle in the low-energy region still remains. Similar reduction of the peak heights by the Coulomb force is also seen in the vector analyzing power of the deuteron, iT11(θ). Other observables are rather similar to the predictions by meson-exchange potentials, including discrepancies of deuteron breakup differential cross sections from experiment for some particular kinematical configurations. The systematic KVI data of the 1H(d⃗, 2p)n scattering at Ed = 130 MeV are reasonably reproduced for breakup differential cross sections and deuteron analyzing powers.

Microscopic description of α + α bremsstrahlung from a realistic nucleon-nucleon interaction

The α + α bremsstrahlung is studied in a microscopic cluster approach with the Generator Coordinate Method associated with the Microscopic R-matrix Method. Two effective nucleon-nucleon interactions are considered: the Minnesota potential and a potential derived from the realistic Argonne AV18 potential by the Unitary Correlation Operator Method. The influence of the nucleon-nucleon interactions are discussed and the results are compared with experimental data.

The effects of strong magnetic fields on neutron star structure: lowest order constrained variational calculations

We investigate the effects of strong magnetic fields upon the large-scale properties of neutron and protoneutron stars. In our calculations, the neutron star matter was approximated by pure neutron matter. Using the lowest order constrained variational approach at zero and finite temperatures, and employing AV18 potential, we present the effects of strong magnetic fields on the gravitational mass, radius, and gravitational redshift of neutron and protoneutron stars. It is found that the equation of state for a neutron star becomes stiffer with an increase of magnetic field and temperature. This leads to larger values of the maximum mass and radius for the neutron stars.

Off-shell Effect of the Quark-model NN Interaction in the Nd Scattering

Low- and medium-energy nucleon–deuteron (Nd) scattering less than the incident energy 65 MeV per nucleon is examined by using the quark-model nucleon–nucleon (NN) interaction fss2. The off-shell effect of this non-local interaction yields a part of the attractive effect given by the three-nucleon force in the standard description by the meson-exchange potentials. The triton binding energy and the spin-doublet scattering length are well described by fss2 without introducing the three-nucleon force. The nucleon analyzing power is slightly improved from the results by the AV18 potential, but the so-called Ay puzzle in the low-energy region is not essentially solved nor is the similar deficiency of the peak heights seen in the vector analyzing power of the deuteron, iT11(θ). Other observables are rather similar to the predictions by meson-exchange potentials, including disagreements of the deuteron breakup differential cross sections with experiment for some particular kinematical configurations. The space-star anomaly of the nd and pd scattering at EN = 13 MeV is not improved. The accurate and systematic KVI data of the \({^{1}H(\overrightarrow{d}, 2p)n}\) scattering at Ed = 130 MeV are compared with the predictions by fss2 for the breakup differential cross sections and the deuteron analyzing powers.

Calculation of the structural properties of asymmetrical nuclear matter

The structural properties of asymmetrical nuclear matter have been calculated, employing the AV18 potential for different values of proton to neutron ratio. These calculations have also been made for the case of symmetrical nuclear matter with the UV14, AV14 and AV18 potentials. In our calculations, we used the lowest order constrained variational method to compute the correlation function of the system.

Triton photodisintegration in three-dimensional approach

Two- and three- particles photodisintegration of the triton is investigated in a three-dimensional (3D) Faddeev approach. For this purpose the Jacobi momentum vectors for three particles system and spin-isospin quantum numbers of the individual nucleons are considered. Based on this picture the three-nucleon Faddeev integral equations with the two-nucleon interaction are formulated without employing the partial wave decomposition. The single nucleon current as well as $\pi-$ and $\rho-$ like exchange currents are used in an appropriate form to be employed in 3D approach. The exchange currents are derived from AV18 NN force. The two-body t-matrix, Deuteron and Triton wave functions are calculated in the 3D approach by using AV18 potential. Benchmarks are presented to compare the total cross section for the two- and three- particles photodisintegration in the range of $E_{\gamma}<30 MeV$. The 3D Faddeev approach shows promising results.

The effect of density dependent Av18 effective interaction on the ground state properties of heavy closed shell nuclei

Abstract The channel-dependent Argonne Av18 effective two-body interactions (CDEI) which are generated through the lowest order constrained variational (LOCV) calculation for asymmetric nuclear matter with the charge-dependent Av18 bare nucleon–nucleon potential are used to calculate the ground state properties of heavy closed shell nuclei such as 48Ca, 90Zr, 120Sn and 208Pb. The harmonic oscillator basis, and the local density approximation (LDA) are applied to create the relative and the center of mass dependent effective two-body potential. We get more binding with respect to the similar calculation with the Reid types potentials. It is tried to omit the LDA and perform full calculation with the Av18 CDEI for light nuclei. The results indicate that the LDA works quite well. It is also shown that in case of heavy closed shell nuclei and unlike our previous report with Reid68Day interaction, the contributions of higher partial waves ( J > 2 ) are very important for the calculations with Av18 potential and we get reasonable agreement between our calculated binding energies and RMS radii, with those predicated by the others methods, and the experimental data. Finally, the various aspects of channel and density dependent two-body effective interactions are discussed.

THE DENSITY-DEPENDENT Av18 EFFECTIVE INTERACTION AND GROUND STATE OF CLOSED SHELL NUCLEI

The ground state properties of light closed shell nuclei, i.e. 4He, 12C, 16O, 28Si, 32S, 40Ca and 56Ni are studied by using the channel-dependent effective two-body interactions (CDEI's). The CDEI's are generated through the lowest-order constrained variational (LOCV) calculation for asymmetric nuclear matter with the charge-dependent Av18 bare nucleon–nucleon potential. The work is performed on the harmonic oscillator basis, and the local density approximation is applied to create the relative and the center of mass dependent effective two-body potential. Unlike nuclear matter, and similar to our previous calculations with the Reid68 interaction, while the Av18 potential under binds above nuclei up J max = 2 channel, it gives ground state binding energies closer to the experimental data with respect to the Δ- Reid68 and the Reid68 potentials. There are not much difference between the results of Av18 interaction with J max = 5, and those of Reid68Day potential which has been define up to J max = 5. The different CDEI's up to J max = 5 are discussed and the results of our calculations are compared with the other theoretical approaches and experimental data. Finally, it is shown that the contributions of higher partial waves (J&gt;2) are not very important and the two-body kinetic energy in J = 1 channel is roughly twice as that of J = 0 which is not the case for the two-body potential energy.

Higher-q Quasi-elastic 3He Transverse (e,e′) Response in a Two-Fragment Model

Recently (Efros et al. in Phys Rev C81:034001, 2010) we have computed the 3He transverse response in the quasielastic region for momentum transfers up to 700 MeV/c using the AV18 potential with the UrbanaIX three body potential. These calculations were carried out in the active nucleon Breit (ANB) frame. Owing to the use of the ANB frame the disagreement of the conventional non-relativistic calculations with experiment has been removed for q values up to 500 MeV/c. However, for higher q values some disagreement still persists. In order to further study the issue we present here results for RT (q, ω) computed in the Breit and Lab frames with the use of the two-fragment model.

Photodisintegration of3Hin a three dimensional faddeev approach

An interaction of a photon with 3H is invstigated based on a three dimensional Faddeev approach. In this approach the three-nucleon Faddeev equations with two-nucleon interactions are formulated with consideration of the magnitude of the vector Jacobi momenta and the angle between them with the inclusion of the spin-isospin quantum numbers, without employing a partial wave decomposition. In this formulation the two body t-matrices and triton wave function are calculated in the three dimensional approach using AV18 potential. In the first step we use the standard single nucleon current in this article.

A realistic formalism for low-momentum effective interaction in three-dimensional approach

The low-momentum effective interaction V low k has been formulated in the three-dimensional momentum-helicity representation as a function of the magnitude of momentum vectors and the angle between them. As an application, AV18 potential has been used in the model space of Lee–Suzuki method and it has been shown that the low-momentum effective interaction, V low k reproduces the same two-body observables obtained by the bare potential V NN .

The elastic pd scattering analyzing powers and spin correlation coefficients at Elab p = 135 and 200 MeV: Three-nucleon force and relativistic effects

The rich set of data for analyzing powers and spin correlation coefficients in pd elastic scattering at Elabp = 135 and 200 MeV taken at IUCF has been compared to theoretical predictions based on modern nuclear forces. To this aim the three-nucleon Faddeev equations have been solved with standard nucleon-nucleon potentials (AV18, CD Bonn, NijmI and II) alone or combined with the 2π-exchange Tucson-Melbourne three-nucleon force. For the AV18 potential also the Urbana IX three-nucleon interaction has been used. For some spin observables the addition of these three-nucleon forces improves the description of data whereas in other cases the description deteriorates. The relativistic effects for all studied spin observables have been investigated and found to be small. The conclusion is that significant parts of the three-nucleon force are missing.

Testing nuclear forces by polarization transfer coefficients ind(p→,p→)dandd(p→,d→)preactions atEplab=22.7MeV

The proton to proton polarization transfer coefficients K_x^{x'}, K_y^{y'}, K_z^{x'} and the proton to deuteron polarization transfer coefficients K_x^{x'}, K_y^{y'}, K_z^{x'}, K_x^{y'z'}, K_y^{z'z'}, K_z^{y'z'}, K_y^{x'z'} and K_y^{x'x'-y'y'} have been measured in d(\vec p, \vec p)d and d(\vec p, \vec d)p reactions at E^{lab}_p = 22.7 MeV, respectively. The data have been compared to predictions of modern nuclear forces obtained by solving the three-nucleon Faddeev equations in momentum space. Realistic (semi) phenomenological nucleon-nucleon potentials combined with model three-nucleon forces and modern chiral nuclear forces have been used. The AV18, CD Bonn, Nijm I and II nucleon-nucleon interactions have been applied alone or combined with the Tucson-Melbourne 99 three-nucleon force, adjusted separately for each potential to reproduce the triton binding energy. For the AV18 potential also the Urbana IX three-nucleon force have been used. In addition chiral NN potentials in the next-to-leading-order and chiral two- and three-nucleon forces in the next-to-next-to-leading-order have been applied. Only when three-nucleon forces are included a satisfactory description of all data results. For the chiral approach the restriction to the forces in the next-to-leading order is insufficient. Only when going over to the next-to-next-to-leading order one gets a satisfactory description of the data, similar to the one obtained with the (semi) phenomenological forces.

DEPENDENCE OF COULOMB SUM RULE ON THE SHORT RANGE CORRELATION BY USING Av18 POTENTIAL

The Coulomb sum rule (CSR) and structure factor are calculated for inelastic electron scattering from nuclear matter at zero and finite temperature in the nonrelativistic limit. The effect of short-range correlation (SRC) is presented by using lowest order constrained variational (LOCV) method and the Argonne Av18 and Δ-Reid soft-core potentials. The effects of different potentials as well as temperature are investigated. It is found that the nonrelativistic version of Bjorken scaling approximately sets in at the momentum transfer of about 1.1 to 1.2 GeV/c and the increase of temperature makes it to decrease. While different potentials do not significantly change CSR, the SRC improves the Coulomb sum rule and we get reasonably close results to both experimental data and others theoretical predictions.