THE U(5) AND O(6) LIMITS OF THE U(6/12) DYNAMICAL SUPERSYMMETRY

Using the pseudo-spin method, the U(6/12) supersymmetries can be decomposed into seven chains: three chains from the U^B+F(6) symmetries (I,Ⅱ,Ⅲ chains) and three "preserving" the IBM symmetries (I',Ⅱ',Ⅲ' chains). The last one is SU^B+F(3)^* synmetry.The physical meaning of chains Ⅱ and Ⅱ', the so-called SU(3)symutetries was discussed by Warner. That of chains Ⅲ and Ⅲ' was briefly in dicated previously by Vallieres et al. In this paper we will discuss the characteristics as well as the physical meaning of chains I and I', to so-called SU(5) limits, andwcontrast it with the discussion for Ⅲ and Ⅲ'.     

SU(6)W and decays of baryon resonances

The decay rates of baryon resonances assigned to the {70, 1^?} and {56, 2⁺} presentations of SU(6)_W ? O(3) are subjected to a detailed comparison with an SU(6)_W model motivated by the recent work of Melosh. We conclude that SU(6)_W is remarkably successful as an approximate symmetry for decay vertices.     

IBFM form of SU(6/M) supergenerators for microscopic foundation

Canonical generators of the SU(6/M) supergroup are transformed to the IBFM form associated with the graded Schwinger realization which explicitly separates the SU(6)⊕SU(M) subalgebra. In the frame of this supersymmetry scheme we relate the IBFM hamiltonian to the microscopic quasiparticle-phonon hamiltonian.     

q-Deformed SU(1,1) ⊗ SO(6) Spectra of Interacting s,d Bosons in Nuclei

The quantum groups SU_q(1,1) and SU_q(2) are used to describe the interacting s, d bosons system which hae the q-deformed SU(1,1) ⊗ SO(6) dynamic symmetry and a Hamiltonian similar to that of O(6)-limit in the interacting boson model is constructed. Three regions of q-number are taken to analyze the influences of deformation on the deformed SU(1,1) ⊗ SO(6) spectra. It is found that the deformation parameter has important influences on the higher excited states within a quasi- rotational band. Yt isotopes with O(6) characteristics are investigated.     

SU(6) Analysis of Mesonic of B-Mesons

The SU(6) symmetry of strong interactions among light quarks is used to analyse two-body mesonic decays of B-mesons based on the Hamiltonian proposed by He-McKellar- Wu.     

SU(6) × SL(3, R) color quark model

A nonrelativistic color quark model based on the spectrum generating group SU(6)×SL(3, R) is presented. The model unifies SU(6) and the Regge classification with linear L vs m² mass spectrum. Baryons are predicted to belong to the ($\text{56}\text{, L}{}^{\mathrm{P}}\text{= (}\text{even}{}^{\mathrm{+}}\text{)}\text{and}\text{(}\text{70}\text{, L}{}^{\mathrm{P}}\text{= (}\text{odd}{}^{\mathrm{?}}\text{)}$ multiplets of the SU (6) × O(3) group.     

群表示论的物理方法(Ⅴ)——SU3?SO3和SU4?SU2×SU2分类基

本文给出了核物理中常用的SU₃?SO₃(f=1—6)和SU₄?SU₂×SU₂波函数在Gelfand表象中的展开系数。 关键词：     

Persistence of rotational bands in a coupled SU(3) model

To understand better the emergence of rotational structures in a variety of situations, a model in which two SU(3) irreps are coupled via a quadrupole-quadrupole (Q·Q) interaction is considered. Strong coupling of different SU(3) irreps gives rise to low-lying rotor bands. We study the excited bands that occur and the perturbation effects of the rotational decoupling. Persistence of rotational-like bands for a large range of coupling strengths is observed. However, although for very weak interaction strengths the electromagnetic transition rates are consistent with those of the rotor model, the excitation energy ratios look more vibrational, a phenomenon which has been observed in many nuclei.     

DYNKIN'S EMBEDDING METHOD AND SUBALGEBRA CHAINS OF U(6)⊃SU(3)*

Use Dynkin's embedding method to find out the generators of two subalgebra chains of U(6)⊃SU(3).     

Quasiparticle shell-model calculation within multi-phonon subspace and SU(6) boson model

The hamiltonian with quadrupole interaction is diagonalized within the multi-phonon subspace for the cases of ⁷⁴Se, ¹¹⁴Cd and ¹²⁶Xe. The results are compared with those of the SU(6) boson model based on the Tamm-Dancoff phonon and the applicability of the boson model is discussed. As a by-product, the applicability of the quasiparticle random-phase approximation (QRPA) is investigated. It is shown that the SU(6) boson model is much better than the QRPA. The contribution from non-collective phonon degrees of freedom to the many-phonon high-spin states is also discussed.     

sdg boson model in the SU(3) scheme

Basic properties of the interacting boson model with s-, d- and g-bosons are investigated in rotational nuclei. An SU(3)-seniority scheme is found for the classification of physically important states according to a group reduction chain U(15) ? SU(3). The capability of describing rotational bands increases enormously in comparison with the ordinary sd interacting boson model. The sdg boson model is shown to be able to describe the so-called anharmonicity effect recently observed in the ¹⁶⁸Er nucleus.     

Study on the Strong-Coupling Scheme to Conserve the Symmetry SU(3) of the Fermion Dynamical Symmetry Model

The strong-coupling wavefunction to conserve the symmetry SU(3) is discussed in detail. In this scheme, a Hamiltonian to conserve the symmetry SU(3) can be approximately rewritten as new forms in the intrinsic frame. It turns out that the particle-rotor model, the odd-odd nuclear spectra, the negative parity bands and the famous Cranking model etc. can be given microscopically under a certain limits. The scheme also provides an approach to considering any-order finite particle effect and mixture of various representations of SU(3).     

The Interacting Boson Model of Dipole-Octupole Strong Correlations in SU(3) Limit for Positive Parity States

Within the framework of the Usdpf(16) interacting boson model (IBM), the effects of strong correlations of the dipole (p--boson) and the octupole (f--boson) degree of freedom on the positive-parity states of even-even nuclei in SU(3) limit are discussed. It is shown that configurations of an even number of many p- and f-bosons can not only be incorporated into the usual low-lying collective rotational bands, such as the ground state band, β- and γ-vibrational bands, but also naturally form the Kπ＝ 1+, 3+ rotational bands, etc. These results are similar to that of Usdg (15)-IBM and in agreement well with the experimental data of the 176 72 Hf 104 nucleus. Besides, several intraband E2 transition probabilities are given, which are consistent with that of Usd(6)-IBM.     

Dyson-type boson mapping and SU(6) boson model

The Dyson-type boson mapping is applied to realistic cases to show that it is a very promising method for describing nuclear collective motion. Eigenvectors are obtained in the corresponding hermitian boson theory from the results of right- and left-hand-side eigenvalue problems in the Dyson boson theory. The numerical results are compared with those of the SU(6) boson model and exact quasiparticle shell-model calculations within the multi-phonon subspace.     

SU(6)W and πN→ϱN revisited

We point out that the intersection of the Berkeley-SLAC and Saclay signs of πN→?N resonant amplitudes are consistent with ?-broken SU(6)_W if both the 70, L^P = 1^?and 56, L^P = 2⁺ multiplets choose anti-SU(6)_W solutions. The symmetry scheme still fails in that the πN→πΔ relative signs require an SU(6)_W-like solution for the 56, L^P = 2⁺. This failure however now rests on a single incorrect sign prediction among all N? and Δπ amplitudes.     

Simple construction ofSU(3) representations using theSU(2) projection technique

SU(3) representations for theSU(3) SU(2) chain are constructed in a new way usingSU(2) projection operators. TheSU(3) D-functions, presented in new parametrizations, are expressed in terms ofSU(2) D-functions and 6j-symbols.Valuable discussions with Dr. J. Niederle are gratefully acknowledged.     

Wilson loops for U(4) and SU(4) lattice gauge theories in four dimensions

Monte Carlo simulations are used to calculate Wilson loops for pure U(4) and SU(4) gauge theories on a 6⁴ lattice. The first-order phase transitions previously observed in the average action per plaquette for U(4) and SU(4) is also seen in the string tension. U(4) and SU(4) color seem to be confined while U(4) charge in U(4) appears to be deconfined.     

Simultaneous Analysis of the nu(2) Raman and nu(2) + nu(6) Infrared Spectra of the SF(6) Molecule

High-resolution Raman spectra of the nu(2) band of SF(6) have been recorded at a temperature of 195 K (dry ice) and a pressure of 39 mbar. These spectra were analyzed using a new set of programs specially written for XY(6) molecules. These programs, called HTDS (highly spherical top data system) in reference to the set of programs called STDS (spherical top data system written for XY(4) molecules) can be freely accessible through ftp (user anonymous) at jupiter.u-bourgogne.fr or on the web at the URL http://www.u-bourgogne.fr/LPUB/shTDS.html. The study of nu(2) was made using a Hamiltonian developed through the third order. Four parameters were determined. The standard deviation obtained using about 559 data up to J < 61 is 0.0021 cm(-1). This result is used to refine by simultaneous analysis the nu(2) and nu(2) + nu(6) bands of SF(6). This new fit allows the determination for the first time of some nu(6) parameters. The values obtained for this band (forbidden in Raman and in infrared) will be used to study the infrared hot bands in the nu(3) and nu(4) regions. Copyright 2000 Academic Press.     

Baryon number generation in a flipped SU(5) × U(1) model

We consider the possibilities for generating a baryon asymmetry in the early universe in a flipped SU(5) × U(1) model inspired by the superstring. Depending on the temperature of the radiation background after inflation we can distinguish between two scenarios for baryogenesis: (1) after reheating the original SU(5) × U(1) symmetry is restored, or there was no inflation at all; (2) reheating after inflation is rather weak and SU(5) × U(1) is broken. In either case the asymmetry is generated by the out-of-equilibrium decays of a massive SU(3) × SU(2) × U(1) singlet field φ_m. In the flipped SU(5) × U(1) model, gauge symmetry breaking is triggered by strong coupling phenomena, and is in general accompanied by the production of entropy. We examine constraints on the reheating temperature and the strong coupling scale in each of the scenarios.