14072723
A new microscopic approach to the rotational intensity relations: Application of the high-spin cranking formalism
Abstract The intensity relations for electromagnetic transition rates in the rotational coupling scheme have been a basic tool to understand the properties of nuclear collective rotations. In particular the correction terms to the leading-order relation give the response of the intrinsic motion to the Coriolis and centrifugal forces. We propose a simple and systematic method to calculate the matrix elements of intrinsic operators entering the generalized intensity relations that uses the microscopic cranking formalism. Examples are given to show the usefulness of the method.
199673909
Nuclear moments of inertia and wobbling motions in triaxial superdeformed nuclei
The wobbling motion excited on triaxial superdeformed nuclei is studied in terms of the cranked shell model plus random phase approximation. Firstly, by calculating at a low rotational frequency the \gamma-dependence of the three moments of inertia associated with the wobbling motion, the mechanism of the appearance of the wobbling motion in positive-\gamma nuclei is clarified theoretically -- the rotational alignment of the \pi i_{13/2} quasiparticle(s) is the essential condition. This indicates that the wobbling motion is a collective motion that is sensitive to the single-particle alignment. Secondly, we prove that the observed unexpected rotational-frequency dependence of the wobbling frequency is an outcome of the rotational-frequency dependent dynamical moments of inertia.
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
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.
119426197
Nuclear wobbling motion and electromagnetic transitions
Abstract The nuclear wobbling motion is studied from a microscopic viewpoint. It is shown that the expressions not only of the excitation energy but also of the electromagnetic-transition rate in the microscopic RPA framework can be cast into the corresponding forms of the macroscopic rotor model. Criteria to identify the rotational band associated with the wobbling motion are given. Examples of realistic calculations are investigated and some theoretical predictions are presented.
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.
121044567
LHCf detector performance during the 2009-2010 LHC run
Large Hadron Collider forward (LHCf) has successfully completed the operation during the LHC 2009–2010 period and the detectors were removed in July 2010. The event trigger, data analysis and background have been intensively studied in order to derive inclusive single photon and π0 spectra. In this paper, the details of these intensive studies are described.
118633837
Like-Sign Dimuon Asymmetry of B0 Meson and LFV in SU(5) SUSY GUT with S4 Flavor Symmetry
The like-sign dimuon charge asymmetry of the B meson, which was reported in the DO Collaboration, is studied in the SU(5) SUSY GUT model with S4 flavor symmetry. Additional CP violating effects from the squark sector are discussed in Bs- ¯ Bs mixing process. The predicted like-sign charge asymmetry is in the 2σ range of the combined result of DO and CDF measurements. Since the SUSY contributions in the quark sector affect to the lepton sector because of the SU(5) GUT relation, two predictions are given in the leptonic processes: (i) both BR(μ → eγ) and the electron EDM are close to the present upper bound, (ii) the decay ratios of τ decays, τ → μγ and τ → eγ, are related to each other via the Cabibbo angle λc :B R( τ → eγ)/BR(τ → μγ) � λ 2. These are testable at future experiments. Subject Index: 142, 151, 152, 154, 158
28368514
Numerical computation of two-loop box diagrams with masses
Abstract A new approach is presented to evaluate multi-loop integrals, which appear in the calculation of cross-sections in high-energy physics. It relies on a fully numerical method and is applicable to a wide class of integrals with various mass configurations. As an example, the computation of two-loop planar and non-planar box diagrams is shown. The results are confirmed by comparisons with other techniques, including the reduction method, and by a consistency check using the dispersion relation.
28690711
Deviations from tri-bimaximality and quark-lepton complementarity
We study deviations from tri-bimaximality (TBM) and quark-lepton complementarity (QLC) in a model-independent way. The current neutrino experimental data is well approximated by tri-bimaximal generation mixing but the QLC relations are not satisfied with each data of 1σ level. This means that there exist deviations from the complementarity. The same fact for the TBM might be checked in the future neutrino experiments. We discuss such deviations from the TBM and QLC, simultaneously. A new ratio between the deviations is introduced, and some interesting points are presented. We also show predicted correlations among leptonic mixing angles at the points.
117897043
Automatic calculations in high energy physics and GRACE at one-loop
Abstract We describe the main building blocks of a generic automated package for the calculation of Feynman diagrams. These blocks include the generation and creation of a model file, the graph generation, the symbolic calculation at an intermediate level of the Dirac and tensor algebra, implementation of the loop integrals, the generation of the matrix elements or helicity amplitudes, methods for the phase space integrations and eventually the event generation. The report focuses on the fully automated systems for the calculation of physical processes based on the experience in developing GRACE-loop which is a general purpose code applicable to one-loop corrections in the Standard Model. As such, a detailed description of the renormalisation procedure in the Standard Model is given emphasizing the central role played by the non-linear gauge fixing conditions for the construction of such automated codes. These new gauge-fixing conditions are used as a very efficient means to check the results of large scale automated computations in the Standard Model. Their need is better appreciated when it comes to devising efficient and powerful algorithms for the reduction of the tensorial structures of the loop integrals and the reduction of the N > 4 point-function to lower rank integrals. A new technique for these reduction algorithms is described. Explicit formulae for all two-point functions in a generalised non-linear gauge are given, together with the complete set of counterterms. We also show how infrared divergences are dealt with in the system. We give a comprehensive presentation of some systematic test-runs which have been performed at the one-loop level for a wide variety of two-to-two processes to show the validity of the gauge check. These cover fermion–fermion scattering, gauge boson scattering into fermions, gauge bosons and Higgs bosons scattering processes. Comparisons with existing results on some one-loop computation in the Standard Model show excellent agreement. These include e + e - → t t ¯ , W + W - , ZH ; γ γ → t t ¯ , W + W - ; e γ → eZ , ν W and W + W - → W + W - . We also briefly recount some recent development concerning the calculation of one-loop corrections to 3 body final states cross sections in e + e - with the help of an automated system.