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An SU(2)×SU(2) chiral quark model describing the properties and interaction of pions and scalar and vector mesons is considered. The confinement of quarks is introduced in the model by means of an infrared cut-off in the one-loop quark diagrams. This cutoff gives rise to the elimination of the unphysical thresholds of the quark-antiquark pair production. The π-a 1 transitions are taken into account. The model conserves all low-energy theorems. The masses of mesons and the widths of the decays ρ → 2π and σ → 2π are calculated.  相似文献   

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《Physics letters. [Part B]》1988,212(3):343-350
We analyze the Yukawa couplings of the first SU(3)×SU(2)×U(1)Y orbifold models recently obtained. In these models the rank is naturally lowered due to the presence of a Fayet-Iliopoulos term associated with an “anomalous” U(1) in the four-dimensional theory. It is shown that the phenomenological viability of the models selects a favoured class of vacua. In particular, for the specific examples considered, some twisted fields with one moded oscillator acting, must acquire non-vanishing VEVs. However other possibilities may exist. We also find that all the baryon and lepton violating operators can be, in general, avoided in a completely natural way.  相似文献   

5.
SU(3)_C×SU(2)_I×U(1)_Y复合轻子理论   总被引:1,自引:1,他引:0  
假定HiggsYukawa耦合是宇称不守恒的唯一来源,通过取三代并引进超对称性,从而建立了一个SU(3)C×SU(2)I×U(1)Y复合轻子理论。  相似文献   

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本文利用变分─累积展开方法将SU(2)×SU(2)格点手征模型的自由能展开到第五级,分别用主值法和聚点法(accumulation point)确定变分参数,结果表明后者能得到与蒙特卡罗模拟更为一致的内能和比热曲线.  相似文献   

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本文利用置换群CG系数计算了五个粒子以内的所有SU(mn) SU(m)×SU(n)单粒子母分系数.  相似文献   

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The β function behavior for SU(2)×SU(2) chiral model on 2-dimensional random triangle lattice has been studied with Monte Carlo renormalization group method.Its behavior is similar to that of the 4-dimensional SU(2) gauge theory.However,it is smoother from weak to strong coupling regions.There is no nonperturbative peak structure.The asymptotic scaling starts beyond β=1.6.  相似文献   

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Recent data obtained by LEP1 are discussed and their potential implication for the existence of a Z particle. This letter advocates that this fits within the basic tenet of an SU(2)×SU(2) extended theory of the standard model of electroweak interactions. This extended electroweak model is motivated by nonabelian electrodynamics that provides an effective calculus for nonlinear optics.  相似文献   

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本文对8×8, 9×9和10×10三种二维随机格点阵的SU(2)×SU(2)手征模型进行了Monte-Carlo(M-C)模拟, 得到了链作用形式的内能和比热结果. 计算结果表明: 当β≥1.0以后, 系统进入过渡区, 但无明显的连续相变迹象; 其统计涨落则由于有限体积引起的边界效应而致. 结果与四维随机格点的SU(2)理论这Monte Carlo计算基本一致[5,6]. 从而我们相信, 在新的随机格点形式下, 亦可能存在4维SU(N)规范理论和2维SU(N)×SU(N)自旋系统的一致性.  相似文献   

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本文利用置换群CG系数计算了五个粒子以内的所有SU(mn)SU(m)×SU(n)单粒子母分系数。  相似文献   

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本文对超色群为半单群的亚夸克模型结构作了讨论, 具体构造了一个SU(4)×SU(4)禁闭弱作用复合模型, 模型中给出了三代轻质量的复合粒子.  相似文献   

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Nonlinear optics confronts the U(1) theory of electrodynamics with the dilemma of the existence of nonlinear fields. The U(1) group is completely linear and Abelian and causes consideration of an SU(2) theory of electrodynamics. An SU(2) theory of electrodynamics, with a B 3 magnetic field, means that physics is forced to consider an SU(2) × SU(2) electroweak theory. It is then demonstrated that the B 3 field exists on the physical vacuum defined by the Higgs symmetry breaking of this extended electroweak theory.  相似文献   

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In this letter a discussion is offered on how symmetry breaking of a theory with twisted bundle of two chiral SU(2) bundles leads to a set of gauge potentials from each group on the physical vacuum that are vector and chiral. The result is that symmetry breaking of this theory leads to massive A 3 transverse modes of the 3-photon along with electromagnetic photons plus the massive neutral and charged weakly interacting bosons. The electromagnetic sector is demonstrated to be a massless vector field and the remainder is a broken chiral field theory.  相似文献   

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本文提出一种SU(4)⊙SU(2)⊙SU(1)统一模型. 在此模型中, 层子和轻子放于同一个多重态中, 所以它们有耦合, 但这种耦合不会导致质子衰变, 只对高能散射有效应. 此模型预言了有两种中性中间玻色子, 还算得了sin2θw=0.25, 并可使中微子有合理的质量.  相似文献   

16.
假定HiggsYukawa耦合是宇称不守恒的唯一来源,通过取三代并引进超对称性,从而建立了一个SU(3)C×SU(2)I×U(1)Y复合轻子理论.  相似文献   

17.
用蒙特卡洛重正化群方法讨论了二维随机三角点阵上SU(2)×SU(2)手征模型的β函数行为,得出它的行为与四维SU(2)规范理论的β函数相似,但强、弱耦合区的过渡更为平滑,不存在尖锐的小峰,标度区从β=1.6开始.  相似文献   

18.
The β function behavior for SU(3)×SU(3) chiral model on 2-demensional random triangle lattice has been studied with Monte Carlo renormalization group method.The behavior is similar to that of the 4-dimensional SU(3) gauge theory,but it has a smoother transition from weak to strong coupling regions.There is no nonperturbative peak structure.The asymptotic scaling starts beyond β=5.8.  相似文献   

19.
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.  相似文献   

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沈坤  裘忠平 《中国物理 C》1989,13(12):1130-1134
本文应用复合场的有效作用量,研究了同时具有动力学破缺和普通自发破缺情况下,SU(2)×SU(2)σ模型中π介子的质量谱;证明了在考虑了微扰效应后,π介子仍具有质量.在最低阶近似下,π介子的质量谱与我们以前的结论一致.  相似文献   

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