140-162Gd核的低能谱和电磁跃迁的相互作用玻色子模型

采用相互作用玻色子模型研究了140-162Gd偶偶核的低能谱和电磁跃迁,应用一个U(5)→SU(3)的简化哈密顿量很好地描述它们的低能谱和电磁跃迁过渡.结果表明140-162Gd同位素核基本上属于U(5)→SU(3)的过渡核.     

164—182Hf核的低能谱和电磁跃迁的相互作用玻色子模型

采用相互作用玻色子模型研究了^164—182Hf偶偶核的低能谱和电磁跃迁, 应用一个U(5)→SU(3)简化哈密顿量很好的描述它们的低能谱和电磁跃迁过渡. 结果表明^164—182Hf同位素核基本上属于U(5)→SU(3)的过渡核.     

^140-262Gd核的低能谱和电磁跃迁的相互作用玻色子模型

采用相互作用玻色子模型研究了^140-262Gd偶偶核的低能谱和电磁跃迁，应用一个U（5）→SU（3）的简化哈密顿量很好地描述它们的低能谱和电磁跃迁过渡．结果表明^140-262Gd同位素核基本上属于U（5）→SU（3）的过渡核．     

128—150Ce偶偶核的低能谱和电磁跃迁的相互作用玻色子模型

采用相互作用玻色子模型研究了^128—150Ce同位素核的低能正宇称态的能谱和电磁跃迁.应用简单的哈密顿量很好的描述它们的能谱和E2跃过.研究表明,这些偶偶Ce核是属于U(5)到SU(3)过渡核,而¹⁴⁶Ce以后的核基本是完全的转动核.     

原子核形状演变的又一个特征指标E0跃迁及对102—110Pd偶偶核的应用

利用相互作用玻色子模型分别在U(5)—SU(3)和U(5)—O(6)描述下研究了^102—110Pd偶偶核的电单极跃迁.研究表明,这些偶偶Pd核能够用U(5)—SU(3)更好地描述.     

原子核的U(6/20)超对称性及其Spin(6)极限

一、引言相互作用玻色子近似(IBA)模型成功地描写了某些偶偶核的性质。IBA模型有三种极限对称性:1)U(5)极限,相当于几何振动核,2)U(3)极限,相当于一种特殊的对称转动核,3)O(6)极限,相当于γ——非稳转动核。在这三种极限对称性下,可以求出IBA哈密顿量的解析解,而三种极限之间的中间结构可用数值计算来求解。近几年来,许多人用相同方法致力于研究奇核的性质,例如美国Drexel组在1983年9月苏州核集体激发态国际会议上就I(6/20)超对称性曾作过报告。相互作用玻色子-费米子近似(IBFA)模型可以求解奇质量核。这时哈密顿量为     

走向统一的自然力 强力、弱力和电磁力的大统一(Ⅰ)

<正>杨-密尔斯规范场、弱电统一理论和粒子物理夸克模型的发现,使人们认识到,不仅电磁力可用U(1)规范场来描述,而且弱电力和强力也可分别用U(1)SU(2)和SU(3)规范场来描述。于是,用U(1)SU(2)SU(3)规范场来统一描述强力、弱力和电磁力便成为粒子物理的标准模型。本讲第一部分通过引入量子概念、建立量子力学,进而介绍能够完     

极性晶体中与形变势相互作用的表面极化子

有不少的极性晶体,电子与表面光学(SO)声子耦合强,但与表面声学(SA)声子耦合弱.研究电子与SO声子耦合强,与SA声子耦合弱的极性晶体中与形变势相互作用的表面极化子的性质.采用改进了的线性组合算符和微扰法导出了极性晶体中与形变势相互作用的表面极化子的有效哈密顿量.在计及电子在反冲效应中发射和吸收不同波矢的声子之间的相互作用时,讨论对表面极化子的有效哈密顿量、有效质量和有效相互作用势的影响.     

相互作用玻色子-费米子模型与“回弯”现象

本文给出了一种相互作用玻色子-费米子模型哈密顿量,在先辈数v≤2的情况下对此模型哈密顿量进行了求解和讨论。结果表明,“回弯”现象的一系列特性可以被很好地描述。     

原子核的形状相变

简要回顾原子核形状相变研究的现状，并将相干态理论与角动量投影方法相结合，在不区分质子玻色子和中子玻色子的相互作用玻色子模型（IBM-1）框架下，对角动量驱动的轴对称情况下的具有U（5）、SU（3）对称性以及两种对称性之间过渡区的原子核的形状相变进行了具体研究。We review the status of the research of nuclear shape phase transitions in this paper. Meanwhile, by taking the coherent state theory and angular momentum projection method, we study the shape phase transitions of axially symmetric even-even nuclei with U（5） symmetry, SU（3） symmetry and those in the transitional region of the two symmetries in the framework of Interacting Boson Model-1 （IBM-1）, which does not distinguish the proton bosons from neutron bosons.     

Isospin and mixed symmetry structure in ~(26)Mg

The isospin excitation states and electromagnetic transitions of the ²⁶Mg nucleus are studied with the isospin-dependent interacting boson model (IBM-3). The mixed symmetry states at low spin and the main components of the wave function for some states are also analyzed. The results show good agreement with the available experimental data. From the IBM-3 Hamiltonian expressed in Casimir operator form, the ²⁶Mg is also proved to be a transition nuclei from U(5) to SU(3).     

Mixed Symmetry States in Even—Even ^96—108Mo Nuclei

Excitation energies and electromagnetic transition strengths in even-even ^96-108Mo nuclei have been described systematically be using the proton-neutron interacting boson model (IBM-2).It appears that the properties of low-lying levels in these isotopes,for which the comparison between experiment and theory is possible,can be satisfactorily described by the IBM-2 model,provided proper account is taken of the presence at low energy of states having a mixed-symmetry character.It seems possible to identify,in each isotope,a few states having such a character,the lowest ones being either 22^ or 23^ levels.It is found that these nuclei are in the transition from U(5) to SU(3).     

THE VARIATIONAL CALCULATION OF MASS GAP IN 2+1 DIMENSIONAL SU(2) LGT

A variational calculation of the mass gap in 2+1 dimensional SU(2) lattice gauge theory by using a Hamiltonian which possesses exact ground state and correct continuum limit is made.In the range 1.3≤1/g²≤7,a good scaling behaviour am=2.28g² is obtained,which is in agreement with weak-coupling perturbation theory and the results obtained by another Hamiltonian which does not possess correct continuum limit.     

Nuclear Structure and Electromagnetic Transitions Investigation in Er Isotopes within Framework of Interacting Boson Model

Interacting Boson Model-2 (IBM-2) is used to determine the Hamiltonian for Er nuclei. Fit values of parameters are used to construct the Hamiltonian, energy levels and electromagnetic transitions (B(E2), B(M1)) multipole mixing ratios (δ(E2/M1)) for some even-even Er nuclei and monopole transition probability are estimated. New ideas are used for counting bosons number at N = 64 and results are compared with previous works.     

Study of the <Superscript>190</Superscript>Hg Nucleus: Testing the Existence of U(5) Symmetry

In this paper, we have considered the energy spectra, quadrupole transition probabilities, energy surface, charge radii, and quadrupole moment of the¹⁹⁰Hg nucleus to describe the interplay between phase transitions and configuration mixing of intruder excitations. To this aim, we have used four different formalisms: (i) interacting boson model including configuration mixing, (ii) Z(5) critical symmetry, (iii) U(6)-based transitional Hamiltonian, and (iv) a transitional interacting boson model Hamiltonian in both interacting boson model (IBM)-1 and IBM-2 versions which are based on affine \( \widehat{SU\left(1,1\right)} \) Lie algebra. Results show the advantages of configuration mixing and transitional Hamiltonians, in particular IBM-2 formalism, to reproduce the experimental counterparts when the weight of spherical symmetry increased.     

Dynamic microscopic basis for IBM-2: A new approach

A dynamic approach, based on deformed Hartree-Fock solution of a nucleus, is suggested for obtaining correlated identical nucleon pair wave function for neutrons and protons. Expressions for single pair energies and two pair interaction matrix elements amongst the neutron and proton pairs in the microscopic fermion basis are presented. These matrix elements define the IBM-2 Hamiltonian through Marumori mapping. The entire procedure is illustrated by obtaining the IBM-2 spectra of²⁰Ne,⁴⁴Ti,⁶⁰Zn and⁹⁴Mo and comparing them with shell model (SM) and/or experimental results. The Yrast levels given by our calculations match well with those of the SM and the experimental results for all the four nuclei, while the non-Yrast levels do not barring the case of⁹⁴Mo. This is due to the loss of isospin symmetry for light nuclei in IBM-2. These results are discussed in detail.     

IBM-2 calculations of some even-even selenium nuclei

In this study, we determined the most appropriate Hamiltonian that is needed for present calculations of nuclei in the A≅ 80 region by the view of interacting boson model (IBM-2). Using the best-fitted values of parameters in the Hamiltonian, we have calculated energy levels and B(E2) values for a number of transitions in some doubly even Se nuclei. The results were compared with the previous experimental and theoretical data and it is observed that they are in good agreement. The calculations have been extended to Se isotopes with A < 76 for which some B(E2) values are still not known.     

Is the SU(3) pattern evidence for SU(3) symmetry?

The results obtained in this paper show that the SU(3) pattern in the spectra and transition rates of even-even nuclei appear qualitatively as a general feature of a large class of quadrupole-phonon models, independently of SU(3) symmetry. This pattern reflects the truncation of the quadrupole phonon space, incorporated via truncation operator in the fourth-order anharmonic quadrupole-phonon Hamiltonian. Three particular forms of the truncation operator are considered, corresponding to three models, namely the truncated quadrupole-phonon model (TQM), equivalent to the well-known interacting-boson model (IBM), the step-truncated quadrupole-phonon model (STQM), equivalent to a standard anharmonic quadrupole-phonon model and the linearly truncated quadrupole-phonon model (LTQM), introduced here. The results obtained provide a basis for a broader scope for the considerations in the SU(3) limit.