119276089
Roles of deformation and neutron excess on the giant monopole resonance in neutron-rich Zr isotopes
We investigate the roles of deformation on the giant monopole resonance (GMR), particularly the mixing of the giant quadrupole resonance (GQR) and the effects of the neutron excess in the well-deformed nuclei around {sup 110}Zr and in the drip-line nuclei around {sup 140}Zr by means of the deformed quasiparticle-random-phase approximation employing the Skyrme and the local-pairing energy-density functionals. It is found that the isoscalar (IS) GMR has a two-peak structure, the lower peak of which is associated with the mixing between the ISGMR and the K{sup {pi}=}0{sup +} component of the ISGQR. The transition strength of the lower peak of the ISGMR grows as the neutron number increases. In the drip-line nuclei, the neutron excitation is dominant over the proton excitation. We find that for an isovector (IV) excitation the GMR has a four-peak structure due to the mixing of the IS and IV modes as well as the mixing of the K{sup {pi}=}0{sup +} component of the IVGQR. In addition to the GMR, we find that the threshold strength is generated by neutrons only.
118529921
Microscopic description of large-amplitude shape-mixing dynamics with local QRPA inertial functions
We introduce a microscopic approach to derive all the inertial functions in the five-dimensional quadrupole collective Hamiltonian. Local normal modes are evaluated on the constrained mean field in the quasiparticle random-phase approximation in order to derive the inertial functions. The collective Hamiltonians for neutron-rich Mg isotopes are determined with use of this approach, and the shape coexistence/mixing around the N = 20 region is analyzed.
106401285
Shape evolution of giant resonances in Nd and Sm isotopes
Giant multipole resonances in Nd and Sm isotopes are studied by employing the quasiparticle-random-phase approximation on the basis of the Skyrme energy-density-functional method. Deformation effects on giant resonances are investigated in these isotopes, which manifest a typical nuclear shape change from spherical to prolate shapes. The peak energy, the broadening, and the deformation splitting of the isoscalar giant monopole (ISGMR) and quadrupole (ISGQR) resonances agree well with measurements. The magnitude of the peak splitting and the fraction of the energy-weighted strength in the lower peak of the ISGMR reflect the nuclear deformation. The experimental data on ISGMR, isoscalar giant dipole (ISGDR), and ISGQR are consistent with the nuclear-matter incompressibility K � 210‐230 MeV and the effective mass m ∗/m � 0.8‐0.9. However, the high-energy octupole resonance (HEOR) in 144 Sm seems to indicate a smaller effective mass, m ∗ /m � 0.7‐0.8. A further precise measurement of HEOR is desired to determine the effective mass.
119110617
Spin–isospin response of deformed neutron-rich nuclei in a self-consistent Skyrme energy-density-functional approach
We develop a new framework of the self-consistent deformed proton-neutron quasiparticle-random-phase approximation (pnQRPA), formulated in the Hartree-Fock-Bogoliubov (HFB) single-quasiparticle basis. The same Skyrme force is used in both the HFB and pnQRPA calculations except in the proton-neutron particle-particle channel, where an S=1 contact force is employed. Numerical application is performed for Gamow-Teller (GT) strength distributions and $\beta$-decay rates in the deformed neutron-rich Zr isotopes located around the path of the rapid-neutron-capture process nucleosynthesis. It is found that the GT strength distributions are fragmented due to deformation. Furthermore we find that the momentum-dependent terms in the particle-hole residual interaction leads to a stronger collectivity of the GT giant resonance. The T=0 pairing enhances the low-lying strengths cooperatively with the T=1 pairing correlation, which shortens the $\beta$-decay half lives by at most an order of magnitude. The new calculation scheme reproduces well the observed isotopic dependence of the $\beta$-decay half lives of deformed $^{100-110}$Zr isotopes.
54645664
Study of halo structure of C from reaction cross section measurement
Abstract The reaction cross sections for 12,16 C have been measured at the energy of 83 A MeV by a new experimental method. The larger enhancement of the 16 C reaction cross section at the low energy has been used to study the density distribution of  16 C. The finite-range Glauber-model calculations for different density distributions have been compared with the experimental data. The analysis suggests that 16 C mainly has a 14 C(core) + 2n structure and shows a strong contribution of (2s1/2)2 for valence neutrons. A large extension of the neutron density distribution to a distance far from the center of the nucleus suggests the formation of neutron halo in the 16 C nucleus.
119572715
Decoupling of valence neutrons from the core in 16C
Abstract The neutron and proton excitations in 16 C nucleus have been investigated by use of the Coulomb-nuclear interference method applied to the 208 Pb+ 16 C inelastic scattering. Angular distribution of the 16 C nuclei in the inelastic channel populating the first 2 + state has been measured. The neutron and proton transition matrix elements, M n and M p , have been determined from the “Coulomb” and “matter” deformation-length parameters obtained by distorted wave calculations. The M p or its corresponding B (E2;2 + 1 →0 + ) value was found to be extremely small: 0.28±0.06 Weisskopf units consistent with a recent lifetime measurement. Furthermore, the extracted M n / M p ratio has an unexpectedly large value of 7.6±1.7. These results suggest that the 2 + 1 state in 16 C is a nearly pure valence neutron excitation.
16998381
Graviton and Spherical Graviton Potentials in Plane-Wave Matrix Model - overview and perspective -
We briefly review our works for graviton and spherical graviton potentials in a plane-wave matrix model. To compute them, it is necessary to devise a configuration of the graviton solutions, since the plane-wave matrix model includes mass terms and hence the gravitons are not free particles as in the BFSS matrix model but harmonic oscillators or rotating particles. The configuration we proposed consists of a rotating graviton and an elliptically rotating graviton. It is applied to the two-body interaction of spherical gravitons in the SO(6) symmetric space, and then to that of point-like gravitons in the SO(3) symmetric space. In both cases the leading term of the resulting potential is 1/r^7. This result strongly suggests that the potentials should be closely related to the light-front eleven-dimensional supergravity linearized around the pp-wave background.
121806959
Measurements of interaction cross sections for light neutron-rich nuclei at relativistic energies and determination of effective matter radii
Abstract We measured the interaction cross sections ( σ I ) of 10,11B, 12–20C, 14–23N, 16–24O and 18–26F on carbon targets at energies of around 950 A MeV. We then deduced the effective matter radii of the nuclei by a Glauber-model analysis. Based on the assumption of a core plus a valence neutron structure, we applied a Glauber-model analysis for a few-body system adapted for nuclei with an odd neutron number. We also deduced the effective nucleus-matter densities as well as some spectroscopic information for selected nuclei. Evidence for a one-neutron halo structure was found for 22N, 23O and 24F, as well as 19C.
9703916
Thermodynamic behavior of fuzzy membranes in pp-wave matrix model
Abstract We discuss a two-body interaction of membrane fuzzy spheres in a pp-wave matrix model at finite temperature by considering the system that a fuzzy sphere rotates with a constant radius r around the other one sitting at the origin in the SO ( 6 ) symmetric space. This system of two fuzzy spheres is supersymmetric at zero temperature and there is no interaction between them. Once the system is coupled to the heat bath, supersymmetries are completely broken and non-trivial interaction appears. We numerically show that the potential between fuzzy spheres is attractive and so the rotating fuzzy sphere tends to fall into the origin. The analytic formula of the free energy is also evaluated in the large N limit. It is well approximated by a polylog function.