Phase Structure of Z3 Lattice Gauge Theory Coupled With the Higgs Field

in the scheme of Migdal-Kadanoff renormalization group transformation, the Phase structure of Z₃ lattice gauge theory coupled with the Higgs field in four dimension space is studied.The phase diagram shows that among the three of the Higgs egion, confined region and free charge region,the first two regions are smoothly connected with each other.     

A REAL-SPACE RENORMALIZATION-GROUP ANALYSIS FOR Z2 LATTICE GAUGE THEORY COUPLED TO A HIGGS FIELD

We present a real-space renormalization-group analysis for Z₂ lattice gauge theory coupled to a Higgs field in four dimension,the results show a phase diagram in which the Higgs and confined region are smoothly connected.     

THE CONSTRUCTION OF A TWO-LOOP FINITE SUPERSYMMETRY SU(5) MODEL

By solving the constraint equations of two-loop finiteness another type of two-loop finite SU(5) ground unified model is given in this paper.There is only one pair of light Higgs doublet,and the other Higgs particles are all superheavy (～M_x).The ordinary CKM-mixing can be obtained only in the low energy region.     

A POSSIBLE SU(9) GRAND UNIFIED MODEL

In this letter, we propose a Higgs mechanism which is different from the usualone at the first step of spontaneous symmetry breaking. Using this new Higgs mechanismwe discuss an SU(9) model which can accommodate three generations of light fer-mions and sustains the asymptotic freedom of SU(3)_c.     

格点Z_4 Higgs场－规范场体系的相结构

用Ｍｉｇｄａｌ－Ｋａｄａｎｏｆｆ重整化群方法对Ｚ４Ｈｉｇｇｓ场─—规范场体系进行了研究，给出了四维时空的相互作用耦合常数递推关系和体系的相图，发现Ｈｉｇｇｓ相与禁闭相是连通的．     

Neutral Higgs Effects on Rare Decay B→Xsl+l－ in the T2HDM

We calculate the new physics contributions to the branching ratios of the rare decays B→X_sl⁺l^－(l=e,μ) induced by neutral Higgs bosons loop diagrams in the top quark two-Higgs-doublet model (T2HDM). From the numerical calculations, we find that (a) the neutral Higgs boson's correction to B→X_sl⁺l^－ decays interferes constructively with its standard model counterpart, but small in magnitude; (b) the neutral Higgs contributions to the branching ratio of B→X_sl⁺l^－ decay can be neglected safely if their masses are larger than 100GeV and tanβ≤40.     

SU(3)C×SU(2)I×U(1)Y Theory of Composite Leptons

Assuming Higgs Assuming coupling to be the only origin of parity non-conservation, an SU(3)_C×SU(2)_I×U(1)_Y theory of composite leptons is established in the Scheme of three generations and supersymmetry.     

Rare decays B0s,d→l+l－ in a top quark two-Higgs-doublet model

In the framework of T2HDM, we calculated the new physics contributions involving neutral Higgs bosons to the branching ratios of B⁰_s,d→l⁺l^－ (l=e, μ) decays. Comparing the theoretical predictions with the experimental upper-limits, we found that (a) The data of Br(B⁰_d→l⁺l^－) give the upper bound on tanβ: tanβ≤22, while Br(B⁰_s→l⁺l^－) give tanβ≤12 for fixed δ=0°, m_H+=350 GeV, m_H0=160 GeV, m_h0=115 GeV and m_A0=120 GeV; (b) A light neutral Higgs boson mass m_h0 (m_A0) less than 50 GeV (120 GeV) is excluded by the data of branching ratios for B⁰_s,d→l⁺l^－(l=μ) decays with tanβ=10; (c) The bounds on m_h0 and tanβ, or m_A0 and tanβ are strongly correlated: a smaller (larger) tanβ means a lighter (heavier) neutral Higgs boson.

     

On the Observation Effects of Higgs Particle in e+e—→bb Z0 and tt－Z0 at LEP Ⅱ and NLC

According to the Minimal Standard Model and the Extended Standard Model with two Higgs doublets, we calculated the total cross sections and differential cross sections for the e⁺e^—→bb Z⁰ and tt－Z⁰ at the LEP Ⅱ and NLC energies in order tO study the possible observational effects of the Higgs particle. We found that the observation for the e⁺e^—→bb Z⁰ can give the information on the Higgs particle as long as the mass of the Higgs particle M_H≤140GeV. However, for the e⁺e^—→tt－Z⁰ the effect from Higgs particle will be completely suppressed by the electrowead background and cannot be observed, no matter whether the Higgs particle is heavy or light.     

顽火辉石(Mg0.92,Fe0.08)SiO3的冲击相变和高压状态方程及其地球物理意义

 用阻抗匹配法和电探针技术在48~140 GPa冲击压力范围内对化学组分为(Mg_0.92, Fe_0.08)SiO₃、初始密度为3.06 g/cm³的天然顽火辉石进行了冲击压缩实验。根据本工作13发实验数据，结合McQueen等人的数据可以看出，(Mg_0.92, Fe_0.08)SiO₃顽火辉石在冲击压缩过程中，大约经历三个明显区域：低压相区，压力范围为0~40 GPa；混合相区，压力范围为40～67 GPa；高压相区，压力范围为68～140 GPa。在低压相区，D-u关系已由McQueen给出；而在高压相区（68～140 GPa），可由本实验数据得到。由叠加原理计算得到的混合物(Mg_0.92, Fe_0.08)O(Mw)+SiO₂(St)的D-u关系及p-ρ关系曲线明显偏离了实验数据的拟合曲线，从而排除了在高达140 GPa冲击压力下，钙钛矿结构的(Mg_0.92, Fe_0.08)SiO₃发生向氧化物化学分解相变的可能性。对高压相区的实验数据进行拟合，可以得到(Mg_0.92, Fe_0.08)SiO₃钙钛矿的Grüneisen参数γ。通过三阶Birch-Murnaghan有限应变状态方程，由冲击波实验数据得到了零压等熵体积模量K_0S=259.6(9) GPa及其对压力的一阶偏导数K′_0S=4.20(5)，其ρ₀=4.19 g/cm³。(Mg_0.92, Fe_0.08)SiO₃钙钛矿冲击压缩下的密度数据与PREM密度剖面吻合很好，支持钙钛矿为主要成分的下地幔模型。     

Multi-layer structure in the strongly coupled 5D abelian Higgs model

We explore the phase diagram of the five-dimensional anisotropic Abelian Higgs model by Monte Carlo simulations. In particular, we study the transition between the confining phase and the four-dimensional layered Higgs phase. We find that, in a certain region of the lattice parameter space, this transition can be first order, and that each layer moves into the Higgs phase independently of the others (decoupling of layers). As the Higgs couplings vary, we find, using mean field techniques, that this transition may probably become second order. Received: 21 December 2001 / Published online: 12 April 2002     

格点Z3规范场–Higgs场耦合体系的相结构

用Migdal–Kadanoff重整化群方法研究了四维时空中的格点Z₃规范场与Z₃-Higgs标量场耦合体系,得到了该体系的耦合常数递推关系和相图,结果表明Z3耦合体系的耦合常数递推关系中的项与Z₂、Z₄耦合体系的耦合常数递推关系中的项不存在一一对应关系.     

DISCUSSION OF A SU(2)×U(1)×S3 MODEL WITH TWO HIGGS DOUBLETS AND CALCULATION OF CABIBBO-LIKE-PARAMETERS

In this paper a SU(2)×U(1)×S₃ model with two Higgs doublets is discussed in detail. It is shown that besides the case discussed by Segre et al., there is another physically interesting case. We investigate the latter in detail. In This case, taking the quark masses and the Cabibbo angle θ₁ as input parameters, we can obtain Cabibbo angles θ₂ and θ₃ which have the same order of magnitude as θ₁. Finally the appearance of a pseudo Goldstone boson in the model is discussed, a method to overcome the difficulty is given, and the physical results of this case which do not contradict with the experiments are discussed.     

Wave functions and spectrum in hot electroweak matter for large Higgs masses

We present results for the wave functions and the screening mass spectrum for quantum numbers , and in the three-dimensional SU(2)–Higgs model near to the phase transition line below the endpoint and in the crossover region. Varying the 3D gauge couplings we study the behaviour along a line of constant physics towards the continuum limit in both phases. In the crossover region the changing spectrum of screening states versus temperature is examined showing the aftermath of the phase transition at lower Higgs mass. Different to smearing concepts we used large sets of operators with various extensions allowing to identify wave functions in position space. Received: 4 August 1998 / Published online: 2 November 1998     

Mean field theory and the SU(2) adjoint Higgs model

Three versions of the mean field approximation are applied to determine the phase diagram of the SU(2) adjoint Higgs model. In two of these, one with gauge fixing and one without, the Higgs action is integrated exactly. In the third version, the Higgs and Wilson parts of the action are treated on equal footing. The results, when compared to those from Monte Carlo simulations, suggest that more accurate simulations are needed in the crossover region.     

THE ONE PION EXCHANGE POTENTIAL AT FINITE TEMPERATURE

By means of the imaginary time Greer's function method,we extend the One Pion Exchange Potential (OPEP) of nucleon-nucleon interaction to finite temperature.We sum up all the bubble diagrams and find that the temperature effect to OPEP is small at low temperature region but large at high temperature region.The effective mass of pion field M_π(β) will become imaginary at critical temperature T_c=177MeV.It means that the attractive OPEP will disappear at T_c and the phase transition happens.     

冷压与热压处理对YBa2Cu3O7-δ的结构相变和超导电性的影响

 本文研究了冷压（2.2~5.2 GPa）与热压（2.2 GPa,2.50~950 ℃）对YBa₂Cu₃O_7-δ的正交→四方相转变区和超导电性的影响。冷压保持其正交结构,但破坏了超导性,在98 K（失超点）到室温呈半导体特性,再在空气中烧结,可恢复液氮温区的零电阻状态。以Cu锅密封样品,热压处理至950 ℃,不发生Cu的析出。热压处理后,98 K（失超点）到室温呈半导体特性,再经通氧烧结,于86 K出现零电阻。热压处理过程,从450~950 ℃为正交→四方转变区。950 ℃为转变结束温度,大大高于氧气、空气、氮气、真空状态的温度。400 ℃附近为起始转变温度,低于氮气、氧气气氛的温度。因此相变区加宽。T_0-t结束温度升高,与Cu锅的抑制还原作用有密切关系。如降低高压淬火速率（<<10² ℃/s）,或随后辅以氧气氛中的后处理,将有利于获得既有高密度又有高T_c的YBa₂Cu₃O_7-δ超导体。     

室温下Fe62Ni27Mn11（wt%）合金的压致fcc-hcp相变

 本文采用Mao-Bell型金刚石对顶砧（DAC）及高压在位（in situ）粉末X光衍射照相方法研究了Fe₆₂Ni₂₇Mn₁₁（wt%）合金在0~43.2 GPa压力范围内的压致结构相变和等温压缩行为，实验结果表明，该合金在低压时为fcc结构，在19.4 GPa压力附近出现压致fcc→hcp结构相变，直到43.2 GPa一直保持fcc、hcp二相共存；相变过程中，二相的molar体积相同；高压hcp相得晶格参数比值c/a基本上不随压力而变，可以表示为c/a=1.630±0.006；在卸压过程中，hcp相可保持到5.8 GPa，当卸压到常压时，该合金完全恢复到fcc结构；用Murnaghan等温固体状态方程对其压缩数据进行最小二乘法拟合，得到B₀=(166±12) GPa，B₀'=5.2±0.5；本文还给出了该合金的压致fcc→hcp结构相变模型，并对存在很宽的二相共存区间问题进行了初步探讨。     

2024Al的三相物态方程

 给出了铝基合金2024Al的包括固、液、气三相的物态方程。考虑了熔化熵的影响，通过标定，选取了合理的汽化与熔化温度的比值。为了更好地描述稀疏区的状态，将冷压作了分段处理。对低于正常密度的区域，提出了一个新的冷压形式。     

Monte Carlo study of a lattice gauge theory with a radially varied Higgs field

The phase structure of a gauge-scalar (Higgs) field system is studied by Monte Carlo simulations without freezing the radial mode of the scalar field. We consider Z₂ lattice gauge theory coupled to a Higgs field which is approximated by a discrete real one. Most of our analysis is done on a 4⁴ lattice. We find that the phase diagram of our model consists of three distinct phases, Higgs and confined regions being divided by a phase boundary. This phase structure forms a contrast with that presented in the model with a fixed-length Higgs field.