arXiv subjects

Y. Suzuki

Publications and source records attributed to Y. Suzuki.

At least 235 records · Page 13Linked to original sources

arXiv2004

Quark-Model Baryon-Baryon Interaction and its Applications to Hypernuclei

The quark-model baryon-baryon interaction fss2, proposed by the Kyoto-Niigata group, is a unified model for the complete baryon octet (B_8=N, Lambda, Sigma and Xi), which is formulated in a framework of the (3q)-(3q) resonating-group method (RGM) using the spin-flavor SU_6 quark-model wave functions and effective meson-exchange potentials at the quark level. Model parameters are determined to reproduce properties of the nucleon-nucleon system and the low-energy cross section data for the hyperon-nucleon scattering. Due to the several improvements including the introduction of vector-meson exchange potentials, fss2 has achieved very accurate description of the NN and YN interactions, comparable to various one-boson exchange potentials. We review the essential features of fss2 and our previous model FSS, and their predictions to few-body systems in confrontation with the available experimental data. Some characteristic features of the B_8 B_8 interactions with the higher strangeness, S=-2, -3, -4, predicted by fss2 are discussed. These quark-model interactions are now applied to realistic calculations of few-body systems in a new three-cluster Faddeev formalism which uses two-cluster RGM kernels. As for the few-body systems, we discuss the three-nucleon bound states, the Lambda NN-Sigma NN system for the hypertriton, the alpha alpha Lambda system for 9Be Lambda, and the Lambda Lambda alpha system for 6He Lambda Lambda.

nucl-th↗

arXiv2004

Photon-Induced Magnetization Reversal in Single-Molecule Magnets

We use millimeter wave radiation to manipulate the populations of the energy levels of a single crystal molecular magnet Fe8. When a continuous wave radiation is in resonance with the transitions from the ground state to the first excited state, the equilibrium magnetization exhibits a dip. The position of this dip varies linearly with the radiation frequency. Our results provide a lower bound of 0.17 ns for transverse relaxation time and suggest the possibility that single-molecule magnets might be utilized for quantum computation.

cond-mat.mes-hall↗

arXiv2004

Case of Almost Redundant Components in 3 alpha Faddeev Equations

The 3 alpha orthogonality condition model using the Pauli-forbidden bound states of the Buck, Friedlich and Wheatly alpha alpha potential can yield a compact 3 alpha ground state with a large binding energy, in which a small admixture of the redundant components can never be eliminated.

nucl-th↗

arXiv2003

Solving Three-Cluster OCM Equations in the Faddeev Formalism

Two different types of orthogonality condition models (OCM) are equivalently formulated in the Faddeev formalism. One is the OCM which uses pairwise orthogonality conditions for the relative motion of clusters, and the other is the one which uses the orthogonalizing pseudo-potential method. By constructing a redundancy-free T-matrix, one can exactly eliminate the redundant components of the total wave function for the harmonic-oscillator Pauli-forbidden states, without introducing any limiting procedure. As an example, a three-alpha-particle model interacting via the deep alpha alpha potential by Buck, Friedrich and Wheatley is investigated.

nucl-th↗

arXiv2003

The optical potential of $^{6}$He in the eikonal approximation

The new data of the elastic scattering of $^{6}$He+$^{12}$C at about 40 MeV/nucleon are analyzed in the eikonal approximation. The $^{6}$He+$^{12}$C phase-shift function is evaluated completely without any {\it ad hoc} assumption by a Monte Carlo integration, which makes it possible to use a realistic 6-nucleon wave function for a halo nucleus $^{6}$He. The effect of the breakup of $^6$He on the elastic differential cross sections as well as the optical potential is studied at different energies from 40 to 800 MeV/nucleon. PACS number(s): 24.10.-i; 21.60.Ka; 25.60.Bx; 25.10.+s Keywords: Eikonal; Glauber; Monte Carlo; Halo; Breakup

nucl-th↗

arXiv2002

Ab initio approach to s-shell hypernuclei 3H_Lambda, 4H_Lambda, 4He_Lambda and 5He_Lambda with a Lambda N-Sigma N interaction

Variational calculations for s-shell hypernuclei are performed by explicitly including $Σ$ degrees of freedom. Four sets of YN interactions (SC97d(S), SC97e(S), SC97f(S) and SC89(S)) are used. The bound-state solution of $_Λ^5$He is obtained and a large energy expectation value of the tensor $ΛN-ΣN$ transition part is found. The internal energy of the $^4$He subsystem is strongly affected by the presence of a $Λ$ particle with the strong tensor $ΛN-ΣN$ transition potential.

nucl-th↗

arXiv2002

Triton binding energy calculated from the SU_6 quark-model nucleon-nucleon interaction

Properties of the three-nucleon bound state are examined in the Faddeev formalism, in which the quark-model nucleon-nucleon interaction is explicitly incorporated to calculate the off-shell T-matrix. The most recent version, fss2, of the Kyoto-Niigata quark-model potential yields the ground-state energy ^3H=-8.514 MeV in the 34 channel calculation, when the np interaction is used for the nucleon-nucleon interaction. The charge root mean square radii of the ^3H and ^3He are 1.72 fm and 1.90 fm, respectively, including the finite size correction of the nucleons. These values are the closest to the experiments among many results obtained by detailed Faddeev calculations employing modern realistic nucleon-nucleon interaction models.

nucl-th↗

arXiv2002

Monte Carlo integration in Glauber model analysis of reactions of halo nuclei

Reaction and elastic differential cross sections are calculated for light nuclei in the framework of the Glauber theory. The optical phase-shift function is evaluated by Monte Carlo integration. This enables us to use the most accurate wave functions and calculate the phase-shift functions without approximation. Examples of proton nucleus (e.g. p-$^6$He, p-$^6$Li) and nucleus-nucleus (e.g. $^6$He$-^{12}$C) scatterings illustrate the effectiveness of the method. This approach gives us a possibility of a more stringent analysis of the high-energy reactions of halo nuclei.

nucl-th↗

arXiv2002

Three-Cluster Equation Using Two-Cluster RGM Kernel

We propose a new type of three-cluster equation which uses two-cluster resonating-group-method (RGM) kernels. In this equation, the orthogonality of the total wave-function to two-cluster Pauli-forbidden states is essential to eliminate redundant components admixed in the three-cluster systems. The explicit energy-dependence inherent in the exchange RGM kernel is self-consistently determined. For bound-state problems, this equation is straightforwardly transformed to the Faddeev equation which uses a modified singularity-free T-matrix constructed from the two-cluster RGM kernel. The approximation of the present three-cluster formalism can be examined with more complete calculation using the three-cluster RGM. As a simple example, we discuss three di-neutron (3d') and 3 alpha systems in the harmonic-oscillator variational calculation. The result of the Faddeev calculation is also presented for the 3' system.

nucl-th↗

arXiv2002

Redundant Components in the 3 alpha Faddeev Equation Using 2 alpha RGM Kernel

The 3 alpha Faddeev equation using 2 alpha RGM kernel involves redundant components whose contribution to the total wave function completely cancels out. We propose a practical method to solve this Faddeev equation, by eliminating the admixture of such redundant components. A complete equivalence between the present Faddeev approach and a variational approach using the translationally invariant harmonic-oscillator basis is numerically shown with respect to the 3 alpha bound state corresponding to the ground state of 12C.

nucl-th↗

arXiv2001

GPIB Address Converter

A GPIB address converter (GAC) has been constructed. This paper reports on the function and test results. The GAC has two GPIB connectors (upper and lower ports). The upper port has a GPIB primary address, and connected to a GPIB system controller. The lower port acts as a GPIB controller of the lower side GPIB line. The GPIB system controller can access the lower side GPIB devices through the GAC by using an extended two-byte address function. The two-byte address (primary + secondary) is shown in the combination of the GAC address and the address of the lower side device. The GAC converts the secondary address into the primary address of the lower side GPIB device. By using 30 GACs, the GPIB system controller can access 930 devices assigned only primary address.

physics.ins-det↗

arXiv2001

Interactions between Octet Baryons in the SU_6 Quark model

The baryon-baryon interactions for the complete baryon octet (B_8) are investigated in a unified framework of the resonating-group method, in which the spin-flavor SU_6 quark-model wave functions are employed. Model parameters are determined to reproduce properties of the nucleon-nucleon system and the low-energy cross section data for the hyperon-nucleon interaction. We then proceed to explore B_8 B_8 interactions in the strangeness S=-2, -3 and -4 sectors. The S-wave phase-shift behavior and total cross sections are systematically understood by 1) the spin-flavor SU_6 symmetry, 2) the special role of the pion exchange, and 3) the flavor symmetry breaking.

nucl-th↗

arXiv2001

Benchmark Test Calculation of a Four-Nucleon Bound State

In the past, several efficient methods have been developed to solve the Schroedinger equation for four-nucleon bound states accurately. These are the Faddeev-Yakubovsky, the coupled-rearrangement-channel Gaussian-basis variational, the stochastic variational, the hyperspherical variational, the Green's function Monte Carlo, the no-core shell model and the effective interaction hyperspherical harmonic methods. In this article we compare the energy eigenvalue results and some wave function properties using the realistic AV8' NN interaction. The results of all schemes agree very well showing the high accuracy of our present ability to calculate the four-nucleon bound state.

nucl-th↗

arXiv2001

A Realistic Description of Nucleon-Nucleon and Hyperon-Nucleon Interactions in the SU_6 Quark Model

We upgrade a SU_6 quark-model description for the nucleon-nucleon and hyperon-nucleon interactions by improving the effective meson-exchange potentials acting between quarks. For the scalar- and vector-meson exchanges, the momentum-dependent higher-order term is incorporated to reduce the attractive effect of the central interaction at higher energies. The single-particle potentials of the nucleon and Lambda, predicted by the G-matrix calculation, now have proper repulsive behavior in the momentum region q_1=5 - 20 fm^-1. A moderate contribution of the spin-orbit interaction from the scalar-meson exchange is also included. As to the vector mesons, a dominant contribution is the quadratic spin-orbit force generated from the rho-meson exchange. The nucleon-nucleon phase shifts at the non-relativistic energies up to T_lab=350 MeV are greatly improved especially for the 3E states. The low-energy observables of the nucleon-nucleon and the hyperon-nucleon interactions are also reexamined. The isospin symmetry breaking and the Coulomb effect are properly incorporated in the particle basis. The essential feature of the Lambda N - Sigma N coupling is qualitatively similar to that obtained from the previous models. The nuclear saturation properties and the single-particle potentials of the nucleon, Lambda and Sigma are reexamined through the G-matrix calculation. The single-particle potential of the Sigma hyperon is weakly repulsive in symmetric nuclear matter. The single-particle spin-orbit strength for the Lambda particle is very small, in comparison with that of the nucleons, due to the strong antisymmetric spin-orbit force generated from the Fermi-Breit interaction.

nucl-th↗

arXiv2000

Lorentz Angle Measurement for CO2/Isobutane Gas Mixtures

We have developed a Lorentz angle measurement system for cool gas mixtures in the course of our R&D for a proposed JLC central drift chamber (JLC-CDC). The measurement system is characterized by the use of two laser beams to produce primary electrons and flash ADCs to read their signals simultaneously. With this new system, we have measured Lorentz angles for CO2/isobutane gas mixtures with different proportions (95:5, 90:10, and 85:15), varying drift field from 0.6 to 2.0 kV/cm and magnetic field up to 1.5 T. The results of the measurement are in good agreement with GARFIELD/MAGBOLTZ simulations.

hep-ex↗

arXiv2000

Properties of few-electron artificial atoms

The spectra of quantum dots of different geometry (``quantum ring'', ``quantum cylinder'', ``spherical square-well'' and ``parabolic confinement'') are studied. The stochastic variational method on correlated Gaussian basis functions and a large scale shell-model approach have been used to investigate these ``artificial'' atoms and their properties in magnetic field. Accurate numerical results are presented for $N$=2-8 electron systems.

cond-mat.mes-hall↗

arXiv2000

Low Energy Solar Neutrino Detection by using Liquid Xenon

Possibility to use ultra pure liquid Xenon as a low energy solar neutrino detector by means of $ν$+e scatterings is evaluated. A possible detector with 10 tons of fiducial volume will give $\sim$14 events for pp-neutrinos and $\sim$6 events for $^{7}$Be neutrinos with the energy threshold at 50 keV. The detector can be built with known and established technologies. High density of the liquid- Xe would provide self-shields against the incoming backgrounds originating from the container and outer environments. Internal backgrounds can be reduced by distillation and other techniques. Purification of the liquid Xe can be done continuously throughout the experiment. The spallation backgrounds are estimated to be small though an experimental determination is neccessary. The liquid-Xe detector can also provide a significantly better sensitivity for the double beta decay and a dark matter search. However the 2$ν$ double beta decay of $^{136}$Xe would be most background. It could be overcome if the 2$ν$ lifetime is longer than 10$^{22}$yr. However, an isotope separation of $^{136}$Xe is inevitable for a shorter lifetime. The isotope separations would, intoroduce a new opportunity to definitively identify dark matter. The interesting feature in addition to the solar neutrino measurements will also be discussed.

hep-ph↗

arXiv1999

Hyperon Single-Particle Potentials Calculated from SU6 Quark-Model Baryon-Baryon Interactions

Using the SU6 quark-model baryon-baryon interaction recently developed by the Kyoto-Niigata group, we calculate NN, Lambda N and Sigma N G-matrices in ordinary nuclear matter. This is the first attempt to discuss the Lambda and Sigma single-particle potentials in nuclear medium, based on the realistic quark-model potential. The Lambda potential has the depth of more than 40 MeV, which is more attractive than the value expected from the experimental data of Lambda-hypernuclei. The Sigma potential turns out to be repulsive, the origin of which is traced back to the strong Pauli repulsion in the Sigma N (I=3/2) ^3S_1 state.

nucl-th↗