Nuclear Theory·nucl-th

Tuesday·February 2, 2016

16 papers—10 primary·6 cross-listed

01
Ab initio no-core properties of 7Li and 7Be with JISP16 and NNLO_opt interactions
Taihua Heng · James P. Vary · Pieter Maris
We investigate the properties of 7Li with the JISP16 and chiral NNLO_opt nucleon-nucleon interactions and 7Be with the JISP16 interaction in the ab initio no-core full configuration (NCFC) approach. We calculate selected observables that include energy spectra, point proton root-mean-square radii, electromagnetic moments and transitions. We compare our results with experimental results, where available, as well as with results obtained using nucleon-nucleon plus three-nucleon interactions. We obtain reasonable agreement between theory and experiment for low-lying states that are dominated by p-shell configurations.
nucl-thPRC(2017)·16 citations
02
Electron-neutrino scattering off nuclei from two different theoretical perspectives
M. Martini🇧🇪 · N. Jachowicz🇧🇪 · M. Ericson🇨🇭 · V. Pandey🇧🇪 · T. Van Cuyck🇧🇪 · N. Van Dessel🇧🇪
We analyze charged-current electron-neutrino cross sections on Carbon. We consider two different theoretical approaches, on one hand the Continuum Random Phase Approximation (CRPA) which allows a description of giant resonances and quasielastic excitations, on the other hand the RPA-based calculations which are able to describe multinucleon emission and coherent and incoherent pion production as well as quasielastic excitations. We compare the two approaches in the genuine quasielastic channel, and find a satisfactory agreement between them at large energies while at low energies the collective giant resonances show up only in the CRPA approach. We also compare electron-neutrino cross sections with the corresponding muon-neutrino ones in order to investigate the impact of the different charged-lepton masses. Finally, restricting to the RPA-based approach we compare the sum of quasielastic, multinucleon emission, coherent and incoherent one-pion production cross sections (folded with the electron-neutrino T2K flux) with the charged-current inclusive electron-neutrino differential cross sections on Carbon measured by T2K. We find a good agreement with the data. The multinucleon component is needed in order to reproduce the T2K electron-neutrino inclusive cross sections.
nucl-thhep-exhep-phPRC(2016)·78 citations
03
$α$ -cluster excited states in $^{32}$ S
Yuta Yoshida · Yoshiko Kanada-En'yo · Fumiharu Kobayashi
$α$ -cluster excited states in $^{32}$ S are investigated with an extended $^{28}$ Si+ $α$ cluster model, in which the $^{28}$ Si core deformation and rotation, and the $α$ -cluster breaking are incorporated. In the GCM calculation with the extended $^{28}$ Si+ $α$ cluster model, the $α$ -cluster excited states are obtained near the $^{28}$ Si+ $α$ threshold energy. The $^{28}$ Si core deformation and rotation effects, and also the $α$ -clusters breaking in the $^{28}$ Si+ $α$ system are discussed. It is found that the rotation of the oblately deformed $^{28}$ Si core gives a significant effect to the $α$ -cluster excited states whereas the $α$ -cluster breaking gives only a minor effect.
nucl-thPTEP(2016)·2 citations
04
Systematic study of $α$ decay for isomer related nuclei within a two-potential approach
Xiao-Dong Sun · Ping Guo · Xiao-Hua Li
$α$ decay occurs in both ground states and isomers of nuclei. In this work, we use the two-potential approach to systematically study whether isomeric states play a key role on $α$ particle clustering or not. The results indicate the ratios of $α$ decay preformation probabilities of isomers to ground states are found to be around 1.
nucl-thnucl-exPRC(2017)·53 citations
05
Infinitesimal cranking for triaxial angular-momentum-projected configuration-mixing calculation and its application to the gamma vibrational band
Shingo Tagami · Yoshifumi R. Shimizu
Inclusion of time-odd components into the wave function is important for reliable description of rotational motion by the angular-momentum-projection method; the cranking procedure with infinitesimal rotational frequency is an efficient way to realize it. In the present work we investigate the effect of this infinitesimal cranking for triaxially deformed nucleus, where there are three independent cranking axes. It is found that the effects of cranking about three axes on the triaxial energy spectrum are quite different and inclusion of all of them considerably modify the resultant spectrum from the one obtained without cranking. Employing the Gogny D1S force as an effective interaction, we apply the method to the calculation of the multiple gamma vibrational bands in $^{164}$ Er as a typical example, where the angular-momentum-projected configuration-mixing with respect to the triaxial shape degree of freedom is performed. With this method, both the $K = 0$ and $K = 4$ two-phonon gamma vibrational bands are obtained with considerable anharmonicity. Reasonably good agreement, though not perfect, is obtained for both the spectrum and transition probabilities with rather small average triaxial deformation $γ \approx 9^{\circ}$ for the ground state rotational band. The relation to the wobbling motion at high-spin states is also briefly discussed.
nucl-thPRC(2016)·10 citations
06
Equations of motion of test particles for solving the spin-dependent Boltzmann-Vlasov equation
Yin Xia · Jun Xu · Bao-An Li · Wen-Qing Shen
A consistent derivation of the equations of motion (EOMs) of test particles for solving the spin-dependent Boltzmann-Vlasov equation is presented. The resulting EOMs in phase space are similar to the canonical equations in Hamiltonian dynamics, and the EOM of spin is the same as that in the Heisenburg picture of quantum mechanics. Considering further the quantum nature of spin and choosing the direction of total angular momentum in heavy-ion reactions as a reference of measuring nucleon spin, the EOMs of spin-up and spin-down nucleons are given separately. The key elements affecting the spin dynamics in heavy-ion collisions are identified. The resulting EOMs provide a solid foundation for using the test-particle approach in studying spin dynamics in heavy-ion collisions at intermediate energies. Future comparisons of model simulations with experimental data will help constrain the poorly known in-medium nucleon spin-orbit coupling relevant for understanding properties of rare isotopes and their astrophysical impacts.
nucl-thnucl-exPLB(2016)·9 citations
07
Elastic $α$ - $^{12}$ C scattering at low energies in cluster effective field theory
Shung-Ichi Ando (Sunmoon U.)🇰🇷
The elastic $α$ - $^{12}$ C scattering at low energies is studied employing an effective field theory in which the $α$ and $^{12}$ C states are treated as elementary-like fields. We discuss scales of the theory at stellar energy region that the $^{12}$ C( $α$ , $γ$ ) $^{16}$ O process occurs, and then obtain an expression of the elastic scattering amplitudes in terms of effective range parameters. Using experimental data of the phase shifts for $l = 0, 1, 2$ channels at low energies, for which the resonance regions are avoided, we fix values of the parameters and find that the phase shifts at the low energies are well reproduced by using three effective range parameters for each channel. Furthermore, we discuss problems and uncertainties of the present approach when the amplitudes are extrapolated to the stellar energy region.
nucl-thhep-phnucl-exEPJA(2016)·33 citations
08
Two-nucleon excitation from $p$ to $s d$ shell in $^{12, 14}$ C
Cenxi Yuan · Min Zhang · Nianwu Lan · Youjun Fang
The effect of the two-nucleon excitation from $p$ to $s d$ shell is discussed in $^{12}$ C and $^{14}$ C in the frame work of shell model. The recently suggested shell-model Hamiltonian YSOX provides an suitable tool to investigate the $2 ℏ ω$ excitation in $p s d$ region. Because the strength of the $< pp ∣ V ∣ s d s d >$ interaction, which represents the interaction between the $0 ℏ ω$ and $2 ℏ ω$ configurations, is considered in the construction of the YSOX. The level of $^{12}$ C is almost independent on the $< pp ∣ V ∣ s d s d >$ interaction, but excitation energies of certain states in $^{14}$ C are strongly affected by it. Further investigation shows that the percentage of $2 ℏ ω$ configuration in these states is quite different from that of the ground state.
nucl-th0 citations
09
Derivation of anisotropic dissipative fluid dynamics from the Boltzmann equation
E. Molnar🇩🇪 · H. Niemi🇩🇪 · D. H. Rischke🇩🇪
Fluid-dynamical equations of motion can be derived from the Boltzmann equation in terms of an expansion around a single-particle distribution function which is in local thermodynamical equilibrium, i.e., isotropic in momentum space in the rest frame of a fluid element. However, in situations where the single-particle distribution function is highly anisotropic in momentum space, such as the initial stage of heavy-ion collisions at relativistic energies, such an expansion is bound to break down. Nevertheless, one can still derive a fluid-dynamical theory, called anisotropic dissipative fluid dynamics, in terms of an expansion around a single-particle distribution function, $f^_{0 k}$ , which incorporates (at least parts of) the momentum anisotropy via a suitable parametrization. We construct such an expansion in terms of polynomials in energy and momentum in the direction of the anisotropy and of irreducible tensors in the two-dimensional momentum subspace orthogonal to both the fluid velocity and the direction of the anisotropy. From the Boltzmann equation we then derive the set of equations of motion for the irreducible moments of the deviation of the single-particle distribution function from $f^_{0 k}$ . Truncating this set via the 14-moment approximation, we obtain the equations of motion of anisotropic dissipative fluid dynamics.
nucl-thhep-phphysics.flu-dynPRD(2016)·98 citations
10
Investigation of pionic contribution in the lepton and anti-lepton production cross section in p-Cu and p-Pt collision
R. Rostami🇮🇷 · F. Zolfagharpour🇮🇷
For detailed explanation of the experimental results of lepton production cross section in hadronic collisions such as nucleon-nucleon or nucleon-nuclei, it is of great importance to use quarks and sea quarks distribution function inside free and bound nucleons. In this paper the role of pion cloud inside the nucleus in the structure function of Cu and Pt nuclei and the EMC ratio of these nuclei were investigated by using harmonic oscillator model.
nucl-thhep-phAdv.High Energy Phys.(2016)·0 citations

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first authorsco-authorsvia INSPIRE