14513100
MICROSCOPIC DESCRIPTION OF NUCLEAR WOBBLING MOTION ROTATION OF TRIAXIALLY DEFORMED NUCLEI
The nuclear wobbling motion in the Lu region is studied by the microscopic cranked mean-field plus RPA method. The Woods-Saxon potential is used as a mean-field with a new parameterization which gives reliable description of rapidly rotating nuclei. The prescription of symmetry-preserving residual interaction makes the calculation of the RPA step parameter-free, and we find the wobbling-like RPA solution if the triaxial deformation of the mean-field is suitably chosen. It is shown that the calculated out-of-band B(E2) of the wobbling-like solution depends on the triaxial deformation in the same way as in the macroscopic rotor model, and can be used to probe the triaxiality of the nuclear mean-field.
119098407
Microscopic Calculation of the Wobbling Excitations Employing the Woods-Saxon Potential as a Nuclear Mean-Field
The wobbling excitations of the triaxial superdeformed (TSD) bands in the Lu and Hf region are studied by the microscopic framework of the cranked mean-field and the randomphase approximation (RPA). In contrast to the previous works, where the Nilsson potential was used, the more realistic Woods-Saxon potential is employed as a nuclear mean-field. It is pointed out that the original formulation should be slightly modified for general meanfield like the Woods-Saxon potential. The wobbling-like RPA solutions have been found systematically in the nuclei studied and their characteristic properties are investigated in detail. This confirms the wobbling phonon excitations in TSD nuclei from the microscopic calculations. The result of B(E2) values indicates that the triaxial deformation is increasing as a function of spin in the observed TSD bands in 163 Lu. Subject Index: 210, 211, 212
119360363
Microscopic structure of high-spin vibrational states in superdeformed A=190 nuclei
Microscopic RPA calculations based on the cranked shell model are performed to investigate the quadrupole and octupole correlations for excited superdeformed (SD) bands in even-even A=190 nuclei. The K = 2 octupole vibrations are predicted to be the lowest excitation modes at zero rotational frequency. The Coriolis coupling at finite frequency produces different effects depending on the neutron and proton number of nucleus. The calculations also indicate that some collective excitations may produce moments of inertia almost identical to those of the yrast SD band. An interpretation of the observed excited bands invoking the octupole vibrations is proposed, which suggests those octupole vibrations may be prevalent in even-even SD A=190 nuclei.
121954152
The role of spin-orbit potential in nuclear prolate-shape dominance
Abstract It is confirmed, in terms of the Woods–Saxon–Strutinsky method, that the spin–orbit potential plays a decisive role in the predominance of prolate deformation, which has been a long standing problem in nuclear physics. It is originated from the combined effects of the spin–orbit coupling and the diffused surface of the potential, in agreement with the previous work based on a more schematic Nilsson–Strutinsky method. The degree of prolate-shape dominance exhibits an oscillatory behavior with respect to the strength of spin–orbit potential and, the prolate-shape dominance is realized at the proper strength of the spin–orbit potential together with the standard surface diffuseness; this oscillatory behavior disappears in case of small diffuseness corresponding to ellipsoidal cavity. The calculated energy differences between oblate and prolate minima in this Letter are consistent with those of our extensive self-consistent calculations of the Hartree–Fock + BCS method with the Skyrme interaction.
118875141
Dynamical moments of inertia associated with wobbling motion in the triaxial superdeformed nucleus
Abstract.The three moments of inertia associated with the wobbling mode built on the triaxial superdeformed states in the Lu-Hf region are investigated by means of the cranked shell model plus random-phase approximation to the configurations with aligned quasiparticle(s). The result indicates that it is crucial to take into account the direct contribution to the moments of inertia from the aligned quasiparticle(s) so as to realize $\mathcal{J}_x > \mathcal{J}_y$ in positive-$\gamma$ shapes.
119187180
Microscopic study of tetrahedrally symmetric nuclei by an angular-momentum and parity projection method
We study the properties of the nuclear rotational excitations with hypothetical tetrahedral symmetry by employing the microscopic mean-field and residual-interaction Hamiltonians with angular-momentum and parity projection method; we focus on the deformed nuclei with tetrahedral doubly-closed shell configurations. We find that for pure tetrahedral deformation the obtained excitation patterns satisfy the characteristic features predicted by group-representation theory applied to the tetrahedral symmetry group. We find that a gradual transition from the approximately linear to the characteristic rigid-rotor, parabolic energy-vs.-spin dependence occurs as a function of the tetrahedral deformation parameter. The form of this transition is compared with the similar well-known transition in the case of quadrupole deformation.
122500053
A New Treatment of the Scaling Violation for Flavor Singlet Distribution Functions in QCD
In a previous paper (Ref. 1), hereafter, we call I) , Q 2 dependence for the parton distribution functions is extensively studied in the framework of Quantum Chromodynamics (QCD). In the paper I, "kernel function" method (method-2 of I) is proposed to calculate the Q 2 dependent parton distribution functions. This method is intended to obtain the exact solution of Altarelli-Parisi equations. 2 >3> The parton distribution functions f. (x, Q 2) in a hadron are*>
120444359
New results from GRACE/SUSY at 1-loop
We discuss the physical importance of the 1-loop correction for several supersymmetric processes. The on-shell renormalization scheme in the framework of the MSSM is adopted and 1-loop amplitudes are full-automatically calculated with GRACE system. The system GRACE/SUSY is checked by the independence on the nonlinear gauge parameters.
120632797
Radiative Bhabha scattering in special configurations with missing final e+ and/or e-
Abstract An event generator for radiative Bhabha scattering with missing e + and/or e - is developed in electroweak theory. The program can generate events of three configurations, in which single γ, single e and eγ are observed.
96097660
Laser-cooled radioactive francium factory at CYRIC
Abstract A factory of laser-cooled francium (Fr) atoms is being developed to search for the electric dipole moment (EDM) of the electron. The factory has achieved the production of Fr ions of 9 × 10 5  particles/s and transport with a transmission efficiency of 2%. In pilot experiments, the magneto-optical trapping of rubidium (Rb) has been performed using a new ion-to-atom converter. To achieve the Fr trap, the development and design of each of the factory’s components are in progress.
122420983
Monte Carlo Approach to Radiative Processes in e+ e- Annihilation
We present a new approach to radiative processes in e+ e- annihilation based on a Monte Carlo method. This is nothing but the QED version of the parton shower model studied extensively in QCD. It is applicable to both initial and final state radiation but without the interference between these two. To examine the validity of the model, we compare it with the results of the exact calculations up to OCa) and OCa 2 ). Comparison of several distributions shows that the model can give reliable results for practical use. Study of radiative corrections in e+ e- collisions has a long history!) since its importance was recognized in the discovery of ]/CP.2) Until now, most efforts have concentrated on the calculation of O(a) corrections to weak interactions. Precise measurements of properties of the ZO boson, however, required the detailed study of higher order QED corrections. Techniques of calculating some contributions in all order have been developed, such as soft photon summation 3 ) and collinear photon summation. 4 ) Generally speaking, these are methods suitable only for inclusive distributions, and they can hardly be applied to exclusive processes or event genera­ tions. It is obvious that the collinear photon summation has an exact correspondence with the collinear parton summation based on the Altarelli-Parisi equation in pertur­ bative quantum chromodynamics (QCD). The parton shower model was originally proposed to deal with exclusive processes in QCD. 5 ) In this paper we apply this technique to QED and examine its validity for radiative processes. We shall call this new model QED parton shower (QEDPS). Although the development of the model is not difficult in the technical sense, study of its validity is a nontrivial task because a much higher accuracy of calculation is required than in QCD. Recently one of the authors calculated exact O(a 2 ) QED corrections to the initial state of e+ e- annihila­ tion. 6 ) With the help of this calculation, we are able to test the validity of QEDPS in a systematic and quantitative way. The purposes of this paper are to present the formulation of QEDPS in a Monte Carlo method and to show that it is really a practical method to describe radiative processes. Since the parton shower model is applied to the final q, q and gluon system in e+ e- annihilation, QEDPS can also be used to estimate QED radiative corrections to the charged particles in the final state. Thus it is equally applicable to both initial and final state radiation, though the interference between these two states cannot be included at present. In the next section we will give the algorithm of QEDPS. In § 3, comparison will