119334067
Longitudinal transitions of baryon resonances in the constituent quark model
A longitudinal transition operator that satisfies the gauge invariance requirement is introduced in the constituent quark model. The corresponding longitudinal transitions from the ground state of the nucleon to resonances of the baryon are calculated. The study shows that the longitudinal coupling plays an important role in the understanding of the structure of the baryon.
119339630
Quark model study of the eta photoproduction: Evidence for a new S(11) resonance?
An extensive and systematic study of the recent eta photoproduction data up to 1.2 GeV is presented within a chiral constituent quark model. A model embodying all known nucleonic resonances shows clear need for a yet undiscovered third S11 resonance in the second resonance region, for which we determine the mass (1.729 GeV) and the total width (183 MeV). Furthermore, we extract the configuration mixing angles, an important property of the quark-quark interaction in the quark model, for the resonances S11(1535) and S11(1650), as well as for the resonances D13(1520) and D13(1700). Our results agree well with the quark model predictions. In addition, the partial eta N decay widths and/or the photo-excitation helicity amplitudes for the nucleonic resonances S11(1535), S11(1650), P11(1710), P13(1720), D13(1520), D13(1700), D15(1675), and F15(1680) are also obtained in this approach.
55936188
Effect of time-odd mean fields on inertial parameters of the quadrupole collective Hamiltonian
Most current implementations of the quadrupole collective Hamiltonian model do not include the contributions of time-odd mean fields to the moments of inertia and mass parameters (Thouless-Valatin dynamical rearrangement contributions). A hybrid model is introduced that allows a quantitative estimate of these contributions to the inertial functions of a five- dimensional collective Hamiltonian based on microscopic energy density functionals. Fully self-consistent constrained relativistic Hartree-Bogoliubov calculations of triaxial energy surfaces in the β−γ plane are used to determine the parameters of an equivalent pairing-plus-quadrupole (P+Q) Hamiltonian. This Hamiltonian is employed in constrained Hartree-Fock- Bogoliubov (CHFB) plus local quasiparticle random-phase approximation (LQRPA) calculation of the deformation- dependent corrections to the Inglis-Belyaev moments of inertia and cranking mass parameters. This hybrid model is used to evaluate the influence of time-odd mean fields on vibrational and rotational collective masses and investigate their effect on the low-energy collective excitation spectra and transition rates of γ-soft Xe and Ba nuclei.
101147336
Impedance Computation of Main Components in CSNS/RCS
120492049
Octupole degree of freedom for nuclei near 152Sm in a reflection-asymmetric relativistic mean-field approach
The potential energy surfaces of even-even isotopes near 152Sm are investigated within the constrained reflection-asymmetric relativistic mean-field approach using parameter sets PK1 and NL3. It is shown that the critical-point candidate nucleus 152Sm marks the shape/phase transition not only from U(5) to SU(3) symmetry, but also from the octupole deformed ground state in 150Sm to the quadrupole deformed ground state in 154Sm. The important role of the octupole deformation driving pair (?2f7/2, ?1i13/2) is demonstrated based on the components of the single-particle levels near the Fermi surface. In addition, the patterns of both the proton and the neutron octupole deformation driving pairs (?2f7/2, ?1i13/2) and (?2d5/2, ?1h11/2) are investigated.
67842056
Beyond the relativistic mean-field approximation. III. Collective Hamiltonian in five dimensions
The framework of relativistic energy density functionals is extended to include correlations related to the restoration of broken symmetries and fluctuations of collective variables. A new implementation is developed for the solution of the eigenvalue problem of a five-dimensional collective Hamiltonian for quadrupole vibrational and rotational degrees of freedom, with parameters determined by constrained self-consistent relativistic mean-field calculations for triaxial shapes. The model is tested in a series of illustrative calculations of potential energy surfaces and the resulting collective excitation spectra and transition probabilities of the chain of even-even gadolinium isotopes.
121143863
THE DYNAMICAL ISOSPIN EFFECT ON PROTON-INDUCED REACTIONS ON Sn ISOTOPES
In this talk we present a model, Improved Quantum Molecular Dynamics (ImQMD05) model incorporated with a Statistical Decay Model (SDM), to describe intermediate energy proton induced spallation reactions. A good agreement with experimental data of double differential cross sections of emitted neutrons is obtained. We further apply this model to study the isospin effect in proton induced spallation reactions on a series Sn isotope targets. We find that the systematic behavior of the reaction cross sections for Sn isotope targets deviates from the empirical expression obtained by fitting the experimental data for proton induced spallation reactions on target nuclei along β-stability line. The extent of the deviation depends on the density dependence of the symmetry energy strongly. We also find an obvious shift of the elastic scattering angular distribution of emitted protons when the symmetry energy is taken into account for neutron-rich Sn isotope targets and the angle shifted strongly depends on the stiffness of the symmetry energy. The attractive effect of the symmetry potential of target on incident proton directly influences the motion of the incident proton leading to strong isospin effect on the reaction dynamics and thus on these reaction observables. We conclude that the measurement of reaction cross sections and the elastic scattering angular distributions in proton induced spallation reactions on Sn isotopes can provide clear constraint for the density dependence of symmetry energy.
53532246
Associated production of neutral Higgs boson with squark pair in the minimal supersymmetric standard model with explicit CP violation at the CERN LHC
We investigate the associated production of neutral Higgs boson with squark pair in the minimal supersymmetric standard model with and without explicit $CP$ violation, respectively. We show that the dominant productions in both cases are always ones of the lightest neutral Higgs boson associated with the lightest stop pair, which can reach a few pb, in the ranges of parameters allowed by constraints from the electric dipole moment experiments. In most of the parameter space, the total cross sections in the case with explicit $CP$ violation are significantly enhanced, compared with ones without explicit $CP$ violation. For some special parameters, several orders of magnitude enhancement can be obtained.
118197616
Transition to Delta matter from hot, dense nuclear matter within a relativistic mean field formulation of the nonlinear sigma and omega model
An investigation of the transition to $\ensuremath{\Delta}$ matter is performed based on a relativistic mean field formulation of the nonlinear $\ensuremath{\sigma}$ and $\ensuremath{\omega}$ model. We demonstrate that in addition to the $\ensuremath{\Delta}$-meson coupling, the occurrence of the baryon resonance isomer also depends on the nucleon-meson coupling. Our results show that for the favored phenomenological value of ${m}^{*}$ and $K$, the $\ensuremath{\Delta}$ isomer exists at baryon density $\ensuremath{\sim}2$--3${\ensuremath{\rho}}_{0}$ if $\ensuremath{\beta}$=1.31 is adopted. For universal coupling of the nucleon and $\ensuremath{\Delta}$, the $\ensuremath{\Delta}$ density at baryon density $\ensuremath{\sim}2$--3${\ensuremath{\rho}}_{0}$ and temperature $\ensuremath{\sim}0.4$--0.5 fm${}^{\ensuremath{-}1}$ is about normal nuclear matter density, which is in accord with a recent experimental finding.
118420473
Systematic study of 16O-induced fusions with the improved quantum molecular dynamics model
The heavy-ion fusion reactions with 16O bombarding on 62Ni, 65Cu, 74Ge, 148Nd, 180Hf, 186W, 208Pb, 238U are systematically investigated with the improved quantum molecular dynamics (ImQMD) model. The fusion cross sections at energies near and above the Coulomb barriers can be reasonably well reproduced by using this semi-classical microscopic transport model with the parameter sets SkP* and IQ3a. The dynamical nucleus-nucleus potentials and the influence of Fermi constraint on the fusion process are also studied simultaneously. In addition to the mean field, the Fermi constraint also plays a key role for the reliable description of fusion process and for improving the stability of fragments in heavy-ion collisions.
43357197
Probing equilibration with respect to isospin degree of freedom in intermediate energy heavy ion collisions
We have studied equilibration with respect to isospin degree of freedom in four 96 mass systems Ru-96 + Ru-96, Ru-96 + Zr-96, Zr-96 + Ru-96, and Zr-96 + Zr-96 at 100A MeV and 400A MeV with isospin-dependent quantum molecular dynamics. We propose that the neutron-proton differential rapidity distribution is a sensitive probe to the degree of equilibration with respect to the isospin degree of freedom. By analyzing the average N/Z ratio of emitted nucleons, light charged particles, and intermediate mass fragments (IMF), it is found that there exist memory effect in multi fragmentation process. The average N/Z ratio of IMF reduces largely as beam energy increases from 100A MeV to 400A MeV that may result from the change of the behavior of the isotope distribution of IMF charges. The isotope distribution of IMF charges does also show certain memory effect at 100A MeV case but not at 400A MeV case.