禁闭弱作用亚夸克大统一理论

本文讨论了禁闭弱作用亚夸克大统一模型. 在合理的统一能标和禁闭标度条件下, 利用重整化群方法得到超色规范群SU(n)满足n≤3, 大统一规范群是SU(7). SU(8)和SO(14).     

大统一对禁闭弱作用规范模型的限制

本文基于两个条件:10¹⁴GeV≤M_u≤10¹⁹GeV,300GeV≤Λ_hc≤1TeV,得到在禁闭弱作用规范模型中SU(N)超色规范群满足N≤3;大统一规范群的可能候选者为:SU(N)N≥7,SU(N)×SU(N)N≥4,SO(14)和SO(18)。 关键词：     

高自旋超形变带的代数模型研究

介绍高自旋超形变带的研究现状,提出一种可以统一描述超形变带的ΔI=4分岔现象、全同带现象等的代数模型,计算结果表明ΔI=4分岔现象可能起因于具有SO(5)(或SU(5))对称的微扰,全同带现象可能是产生超形变态的平均场具有超对称性的结果.     

二维超对称模型的超对称破缺和Witten指数

构造了一类超势W=(1/n)gφⁿ的二维O(N)对称超对称模型,详细计算了此类模型的Witten指数△。结果表明,当n为偶数时,超对称一定不能破缺,而当n为奇数时,超对称可以破缺。利用大N展开法,还研究了上述模型的超对称自发破缺机制,同时给出了相应的粒子谱。 关键词：     

矢量介子及其激发态的讨论

在Regge唯象下, 首先研究自旋-宇称多重态中六个介子质量间的关系式. 运用验证后的关系式, 重点计算基态矢量介子多重态(1³S₁)中尚未观测到的双重粲-底介子 B_c^*的质量. 还计算了径向激发态2³S₁多重态的介子质量和轨道激发态1³G₅介子九重态的质量. 根据计算结果结合实验数据和其他理论进行讨论, 建议在6355 MeV附近寻找和研究 B_c^*介子, 将 D(2600)和 D_s1(2700)分别作为主要成分为 nc(2³S₁)和 sc(2³S₁)的态进行研究; 分别在5812, 5917, 6896 MeV附近寻找矢量介子第一径向激发态 B^*(2S), B_s^*(2S)和 B_c^*(2S). 建议将 ω₅(2250)安排在1³G₅介子九重态的同位旋标量态, 实验上在2259 MeV附近进一步研究 ρ₅(2350)的性质, 在2438 MeV附近寻找和研究 φ₅(1³G₅). 研究结果对于相关介子的自旋-宇称安排和通过实 验寻找新的介子激发态具有重要的参考价值. 关键词： Regge唯象 矢量介子 质量谱     

基于二缺位钨多酸化合物的二维相关红外光谱研究

通过水热法合成了一例新颖的稀土钨多酸化合物H₂₆(C₂H₈N₂H₂)K(H₂O)[K(H₂O)Nd₈(H₂O)₂(W₃O₁₂)(SiW₁₀O₃₈)₄]·18H₂O 1。该化合物的不对称单元由两个[SiW₁₀O₃₈]^12-通过一个{Nd₄(H₂O)¹²⁺}结构单元和W₃O₁₂连接而成。化合物1簇阴离子通过K离子连接成一维无限链,再通过氢键连接成二维平面结构。针对该化合物,做了一系列表征,测试了其二维相关红外光谱,并对其作了详细分析,结果说明化合物1簇阴离子振动偶极矩对磁...     

Multiquark States and the Mixing of Scalar Meson

In order to describe Kaon-Nucleon scattering data, the mixing of scalar meson $\sigma_{0}$ and $\sigma_{8}$ must be introduced in the chiral SU(3) quark model. Inspired by this, now the mixing of scalar meson is further considered to study some interesting dibaryons in the chiral SU(3) quark model. The results show that the mixing of scalar meson has different effects on these dibaryons.     

S■(12)群表示的填充与强衰变

本文讨论了3~-/2,1~-/2,7~+/2等共振态在SU(12)群表示中的填充及其强衰变,发现16016,35100两个表示中的3~-/2粒子不能衰变到1~+/2和0~-.通过改变运动方程质量项的符号使表示的宇称改变,就能将(3~-/2,8)和(1~-/2,1)填在572表示中,从而使它们能衰变到1~+/2和0~-。但是,(3~-/2,1)和7~+/2仍然不能通过SU(12)对称的有效顶点衰变,本文还详细分析了SU(12)在基本粒子分类和强衰变中的成功之处与局限性,并讨论了这种局限性产生的原因。     

硅中三空位V3-的超精细相互作用的理论计算

利用Koster-Slater的格林函数方法,计算了硅中三空位V₃^-的电子态能级和波函数.结果表明,V₃^-在禁带中有五条能级:E_(A2)=0.417eV,E_(B1)=0.492eV,E_(B2¹)=0.512ev, E_(A1)=0.532eV,E_(B2²)=0.608eV.根据算得的超精细相互作用常数同实验值的比较,定出V₃^-处于B₁态.V₃^-的B₁态点据第1壳层的几率为60.2％,但主要集中在三空位所确定的平面内的二个原子上. 关键词：     

Charmed andϕmeson decay constants from 2+1-flavor lattice QCD

On a lattice with 2+1-flavor dynamical domain-wall fermions at the physical pion mass,we calculate the decay constants of D_s^* , D^* ,and φ .The lattice size is 48^3×96 ,which corresponds to a spatial extension of -5.5 fm,with a lattice spacing of a\approx a≈0.114 fm.For the valence light,strange,and charm quarks,we use overlap fermions at several mass points close to their physical values.Our results at the physical point are f_D=213(5) MeV, f_Ds=249(7) MeV, f_D^*=234(6) MeV, f_Ds^*=274(7) MeV,and f_Ds=241(9) MeV.The couplings of D^* and D_s^* to the tensor current( f_V^T )can be derived from ratios f_D^*^T/f_D^*=0.91(4) and f_Ds^*^T/f_Ds^*=0.92(4) ,respectively,which are the first lattice quantum chromodynamics(QCD)results.We also obtain ratios f_D^*/f_D=1.10(3) and f_Ds^*/f_Ds=1.10(4) ,which reflect the size of heavy quark symmetry breaking in charmed mesons.Ratios f_Ds/f_D=1.16(3) and f_Ds^*/f_D^*=1.17(3) can be taken as a measure of SU(3)flavor symmetry breaking.     

A dynamical theory for the rishon model

We propose a composite model for quarks and leptons based on an exact SU(3)_C × SU(3)_H gauge theory and two fundamental $\text{J=}\text{1}\text{2}$ fermions: a charged T-rishon and a neutral V-rishon. Quarks, leptons and W-bosons are SU(3)_H-singlet composites of rishons. A dynamically broken effective SU(3)_C × SU(2)_L × SU(2)_R × U(1)_B?L gauge theory emerges at the composite level. The theory is “natural”, anomaly free, has no fundamental scalar particles, and describes at least three generations of quarks and leptons.     

Repetition of the quark-lepton states in a supersymmetric composite model with complementarity

In a supersymmetric composite model based on an SU(4)^loc_sc confining theory, complementarity is used to support the symmetry-breaking pattern and spectrum of massless particles in a confining phase. The model is found to accomodate two generations of quarks and leptons as quasi Nambu-Goldstone fermions and another two generations as chiral fermions. Masses of composite particles are examined and the quark-lepton generations are classified according the possible mass splittings. The suppression of dangerous flavor-changing interactions is considered also.     

A realistic supersymmetric GUT model coupled toN=1 supergravity

A systematic method to look for minima inSU(N) SUSY GUT models is developed. A supersymmetric GUT model coupled toN=1 supergravity is proposed. The degeneracy of different vacua is removed and supersymmetry is spontaneously broken.     

Generations of massless composite quarks and leptons

We present a QCD-like composite model in which quarks, leptons and technifermions are three-body systems made out of three kinds of massless elementary fermions t, c and w, each carrying technicolor, color and weak gauge interactions, respectively. Discrete symmetries, remnants of the U(1)_A of the original lagrangian, are responsible for the masslessness of all the quarks and leptons and give the precise meaning of the generations. The model exhibits three generations for both quarks and leptons. Small but non-zero masses of the quarks and leptons are produced by the technicolor condensate of the composite technifermions, which thereby leads to the non-trivial Cabibbo mixing. Proton decays are all forbidden at the mass scale of the QCD-like theory.     

LHC (CMS) discovery potential for models with effective supersymmetry and nonuniversal gaugino masses

We investigate squark and gluino pair production at LHC (CMS) with subsequent decays into quarks, leptons, and the lightest supersymmetric particles (LSP) in models with effective supersymmetry, where the third generation of squarks is relatively light, whilst the first two generations of squarks are heavy. We consider the general case of nonuniversal gaugino masses. The visibility of a signal through an excess over Standard Model background in (n≥2) jets+(m≥0) leptons+E _T ^miss events depends rather strongly on the relation between the LSP, second-neutralino, gluino, and squark masses and decreases with increasing LSP mass. We find that, for a relatively heavy gluino, it is very difficult to detect a SUSY signal even for light third-generation squarks $(m_{\tilde q_3 } \leqslant 1TeV)$ if the LSP mass is close to the third-generation squark mass.     

On the excited quarks and leptons

Using a duality-like finite energy sum rule, we discuss the assumption of having excited fermions at the W scale in a supersymmetric(SUSY) and non-supersymmetric hypercolour theory where quarks and leptons are bound states of fermion and scalar preon constituents. We conclude that a SUSY-like composite model cannot have excited fermions having a mass smaller than 0.5 TeV. A non-SUSY composite model having composite fermions but elementary W bosons can produce an excited fermion mass of the order of M_W provided that the scalar vacuum condensate is of the order of the (TeV)² scale of compositeness.     

Superunification from eleven dimensions

We show how N = 8 supersymmetry can break spontaneously to N = 1 at the Planck scale via a Kaluza-Klein compactification of d = 11 supergravity on the squashed seven-sphere. Features unique to Kaluza-Klein supergravity are (i) the massless gravitino of the N = 1 phase comes from a massiveN = 8 supermultiplet, (ii) the scalars developing nonzero VEVs also belong to massive N = 8 supermultiplets, (iii) parity remains unbroken when N = 8 breaks to N = 1.Next we ask whether the resulting N = 1 theory can provide a realistic SU(3) × SU(2) × U(1) unification and speculate that it might if some of the gauge bosons and fermions are composite as in the EGMZ model. In contrast to their model, however, we avoid unwanted helicities and problems with their non-compact E₇. Moreover, we suggest a scheme in which the electroweak SU(2) × U(1) is a subgroup of the d = 11 general coordinate group but that the strong SU(3) is a subgroup of the d = 11 local Lorentz group and are not, therefore, to be combined into a GUT. The special properties of the seven-sphere also suggest a possible solution of the cosmological constant problem involving fermion condensates.     

Chiral quarks and proton decay

In this paper we calculate the hadronic matrix elements of baryon decay operators using a chiral effective lagrangian with quarks, gluons and Goldstone boson fields. We study in detail the cases where the ΔB = 1 operators arise from supersymmetric SU(5) GUT as well as the minimal SU(5) GUT model. In each model the results depend on two parameters. In particular there is a range of values for the two parameters, where the dominant decay modes in the minimal SU(5) GUT are: p → ηe⁺ and n → π^? e⁺.     

TWO-LOOP-FINITE SUPERSYPiP1ETRIC THEORIES OF SU(n)

In this note we obtain all two-loop finite N=1 supersymmetric Yang-Mills theories of real representations of SU(n) as well as those of complex representations. There are a few candidates which can accommodate three generations of quarks and leptons.     

Argyres-Seiberg Duality and the Higgs Branch

We demonstrate the agreement between the Higgs branches of two ${\mathcal{N}=2}We demonstrate the agreement between the Higgs branches of two N=2{\mathcal{N}=2} theories proposed by Argyres and Seiberg to be S-dual, namely the SU(3) gauge theory with six quarks, and the SU(2) gauge theory with one pair of quarks coupled to the superconformal theory with E ₆ flavor symmetry. In mathematical terms, we demonstrate the equivalence between a hyperk?hler quotient of a linear space and another hyperk?hler quotient involving the minimal nilpotent orbit of E ₆, modulo the identification of the twistor lines.