Topcolor-Assisted Technicolor and the Decay Bc → Ds*γ

Applying the perturbative QCD method, we study the process B_c → D_s^*γ in the topcolor-assisted technicolor model (TATCM), and compare the results with those estimated in the standard model (SM). There are two mechanisms which contribute to the B_c → D_s^*γ process. One proceeds through the short distance b → sγ transition, the other through weak annihilation accompanied by a photon emission. The contribution of weak annihilation is found to be much more important than that of tlie electromagnetic penguin in the TATCM, and the branching ratio, BR (B_c → D_s^*γ), is much smaller than that in the SM.     

Z2 × Z2 Discrete Symmetry in the Left-Right Symmetric Model SU(2)L × SU(2)R × U(l)B-L

From the point that the Higgs fields can be regarded as the gauge fields on a discrete group, we construct a gauge theory of the leftright symmetric model SU(2)_L × SU(2)_R × U(1)_B-L (LRSM) over Z₂ ⊙ Z₂ discrete symmetry.     

The Singlet Axial Vector Coupling in the Effective Meson Baryon Lagrangian

The Goldberger-Treiman (GT) relation in the singlet channel, being consistent with the EMC experimental results, can be manifested in an extended a model in which the chiral symmetry in the singlet channel is realized in the parity doublet model by assuming that the excited nucleon state S₁₁ N(1535) is the parity partner of the nucleon state. The model gives a natural explanation of the smallness of the singlet axial vector coupling g_A⁰ without the necessity to assume a large strange sea contribution, and is unique in explaining the decay rate of N(1535) → N_η as well.     

Derivation of the Bosonic Part of the Electroweak Chiral Lagrangian from a General Underlying Technicolor Theory

Bosonic part of SU(2)_L\otimes U(1)_Y effective chiral Lagrangian for electroweak symmetry breaking is derived from an underlying technicolor theory with no approximation. The underlying theory is assumed to be the most general gauge theory without fundamental scalars. A condensate is required to exist in the theory which breaks SU(2)_L\otimes U(1)_Y dynamically to U(1)_em and the anomaly of the theory caused by gauge interaction must be cancelled. The formulation offers general definitions in terms of underlying theory for the low energy constants in effective chiral Lagrangian.     

STRING THEORY WITH THREE FAMILIES OF CHIRAL FERMIONS

A heterotic string theory is constructed by compactifying directly from 26 to 4 dimensions via a smooth manifold T²²/G. In the low energy limit, there are three families of chiral fermions with exactly the same quantum numbers as thatin the standard supersymmetric SU(3)×SU(2)×XU(1) model. They couple to supergravity and supergauge fields with the gauge symmetry SU(3)_F×SU(3)_c×SU(3)_L×U(1)_YR×U(1)_I3R.     

Production Rate of Ds+Ds- at φ(4030)

By using a generalized relativistic quark pair creation model (QPCM), the hadronic decay processes of φ(4030), assigned as the 3S state of cc, are investigated. The relative rates of φ(4030) → DD, DD^*+DD^*, D^*D^*,and in particular D_s⁺D_s^- are calculated and compared with data. The nodes of the radially excited wavefunctions of charmonium states are found to be significant for these decay processes. Considering the SU(3) suppression factor of ~3 for the s quark pair creation relative to the u and d quarks, we obtain σ(e⁺e^- → φ4(4030) → D_s⁺D_s^-) ~ 0.9 nb.     

Study on the Radiative Decays of B Mesons in the Multiscale Walking Technicolor Model

We calculate PGB (pseudo-Goldstone boson) corrections to the decays B → X_sγ and B → K^*γ in the MWTCM (multiscale walking technicolor model). The presence of PGBs in the MWTCM leads to large enhancements in the rates of B → X_sγ and B → K^*γ. But these results are in conflict with the recent CLEO data on the branching ratios BR (B → X_sγ) and BR(B → K^*γ). If topcolor is further introduced, the calculated results in the topcolor assisted MWTCM can be suppressed and be in agreemet with the CLEO data for a certain range of parameters. We also estimate the branching ratio BR (B → X_sg) in the topcolor assisted MWTCM, and this estimate is roughly one order higher than that in the standard model.     

Gauged Goldstone boson effective action from direct integration of bardeen anomaly

We derive the effective action which describes the anomalous Goldstone boson interactions in the presence of external flavour SU(N)_L×SU(N)_R gauge fields, by a direct integration of the Bardeen anomaly. Through comparison with other results, we are able to elucidate the relationship between anomalies based on different regularization schemes. We also give a compact representation of the anomalous part of the fermionic determinant allowing for a simpler rederivation of our results.     

Composite Higgs scalars

We construct models in which the Higgs doublet whose vacuum expectation breaks SU(2) × U(10 is a bound state of massive strongly interacting fermions. The couplings of the composite Higgs to ordinary fermions are induced by heavy gauge boson exchange in the manner of extended technicolor. Other heavy gauge bosons generate a negative mass term for the Higgs.     

Pole Analysis on Unitarized SU(3)× SU(3) One Loop χPT Amplitudes

We analyze ππ-KK and πη-KK couple channel [1,1] matrix Padé amplitudes of SU(3)× SU(3) chiral perturbation theory. By fitting phase shift and inelasticity data, we determine pole positions in different channels (f₀(980), a₀(980), f₀(600), K₀^*(800), K^*(892), ρ(770)) and trace their N_c trajectories. We stress that a couple channel Breit-Wigner resonance should exhibit two poles on different Riemann sheets and meet each other on the real axis when N_c=∞. Poles are hence classified using this criteria and we conclude that K^*(892) and ρ(770) are unambiguous Breit-Wigner resonances. For scalars the situation is much less clear. We find that f₀(980) is a molecular state rather than a Breit-Wigner resonance, while a₀(980), though behave oddly when varying N_c, do maintain a twin pole structure.     

Mixing of Pseudo-Goldstone Bosons and Effects on HERA High-Q2 Events

We study the mixing of pseudo-Goldstone bosons predicted by technicolor theory and the effects on HERA high-Q² events. We find that: (a) there eyist two F = 0 scalar leptoquarks P₃′ with m(P₃′) = 200 GeV and P₃⁰ with m(₃⁰) =225 GeV for β₁ = β₂ = 0.4; (b) the P₃′ and P₃⁰ can contribute the required cross section to account for the excesses of NC and CC high-Q² events; (c) the coexistence of P₃′ and P₃⁰ may be responsible for the splitting of averaged mass of the H1 and ZEUS high-Q² neutral current events.     

AlH~+离子5个Λ-S态和10个?态的光谱性质以及激光冷却的理论研究

利用考虑Davidson修正的内收缩多参考组态相互作用(icMRCI+Q)方法结合相关一致基组aug-ccpV6Z计算了AlH~+离子前两个离解极限对应的5个Λ-S态和10个?态的势能曲线.为了提高势能曲线的可靠性和精确性,计算中考虑了自旋轨道耦合效应、芯电子价电子相关和标量相对论修正以及将势能外推至完全基组极限.基于得到的势能曲线,获得了束缚和准束缚的4个Λ-S态和8个?态的光谱常数和振动能级,与已有的实验结果符合.计算了2(1/2)→X~2Σ_(1/2)~+和A~2Π_(3/2)→X~2Σ_(1/2)~+跃迁的跃迁偶极距.利用计算的精确的势能曲线和跃迁偶极矩,获得了2(1/2)~(第一势阱)(υ′=0, 1)→X~2Σ_(1/2)~+(υ′′)和A~2Π_(3/2)(υ′=0, 1)→X~2Σ_(1/2)~+(υ′′)跃迁的高度对角化分布的Franck-Condon因子(f_(00)和f_(11))和大的振动分支比;预测了2(1/2)~(第一势阱)(υ′=0, 1)和A~2Π_(3/2)(υ′=0, 1)态短的自发辐射寿命和窄的辐射宽度,这适合于AlH~+离子的快速激光致冷.所需的3束激光冷却波长都在紫外区域.这些结果表明了激光冷却AlH~+离子的可行性.此外,评估了自旋轨道耦合效应对光谱常数、振动能级和激光冷却AlH~+离子的影响.     

Rare Decays B → XS,dνν and XS,d → l+l- in the,Topcolor-Assisted Technicolor Model

We calculate the contributions to the rare decays B → X_S,dνν and X_S,d → l⁺l^- from one-loop Z^o -penguin diagrams in the framework of topcolor-assisted technicolor model. Within the parameter space, we find that: (a) the new contribution from technipions is less than 2% of the standard model prediction; (b) the top-pions can provide a factor of 10 to 30 enhancement to the ratios in question; (c) the topcolor-assisted technicolor model is consistent with the current experimental'data.     

The Three-Pion Decays of the a1(1260)

We investigate the decay of a₁⁺ (1260)→π⁺π⁺π^- with the assumption that the a₁(1260) is dynamically generated from the coupled channel ρπ and KK^* interactions. In addition to the tree level diagrams that proceed via a₁⁺ (1260)→ρ⁰π⁺→π⁺π⁺π^-, we take into account also the final state interactions of ππ→ππ and KK→ππ. We calculate the invariant π⁺π^- mass distribution and also the total decay width of a₁⁺ (1260)→π⁺π⁺π^- as a function of the mass of a₁(1260). The calculated total decay width of a₁(1260) is significantly different from other model calculations and tied to the dynamical nature of the a₁(1260) resonance. The future experimental observations could test of model calculations and would provide vary valuable information on the relevance of the ρπ component in the a₁(1260) wave function.     

Low-Energy Contributions to B (D) → π Form Factor

We calculate low-energy contributions to the weak form factors of B (D) → π in the frameworks of heavy-light chiral perturbation theory (HLCPT) including vector meson effects. The calculation is done to the order 1/Λ_csb³ in the expansion with respect to Λ_csb (Λ_csb is the chiral symmetry breaking scale) at O(1) in 1/m_Q expansion and to 1/Λ_csb² at l/m_Q. It is found that nonperturbative effects dominate B (D) → π form factors and the values are comparable with those from quark model approach.     

t夸克圈对TC理论的中性PG玻色子反常耦合的影响

推出了TC理论的中性PG玻色子与规范玻色子(Z、γ、g)的总耦合拉氏量,计算了t夸克圈对中性PG玻色子衰变宽度的影响.结果表明t夸克圈能有效地增加反常耦合强度,为在实验上寻找PG玻包子提供了理论依据.     

CP-Violation from Spin-1 Resonances in a Left-Right Dynamical Higgs Context

New physics field content in the nature, more specifically, from spin-1 resonances sourced by the extension of the SM local gauge symmetry to the larger local group SU(2)_L ⊗ SU(2)_R U(1)_B-L, may induce CP-violation signalling NP effects from higher energy regimes. In this work we completely list and study all the CP-violating operators up to the p⁴-order in the Lagrangian expansion, for a non-linear left-right electroweak chiral context and coupled to a light dynamical Higgs. Heavy right handed fields can be integrated out from the physical spectrum, inducing thus a physical impact in the effective gauge couplings, fermionic electric dipole moment, and CP-violation in the decay h→ ZZ^* → 4l that are briefly analysed. The final relevant set of effective operators have also been identified at low energies.     

Constraints on Technicolor Models from Inclusive Decay of B Meson

Corrections to the branching ratio BR (B → X_s γ) from technipions and top pions appeared in technicolor models are investigated. We found that: (a) the multiscale walking technicolor model is ruled out since it is conflict with the CLEO data; (b) the topcolor-assisted technicolor model is consistent with the CLEO data of BR(B → X_s γ) for a certain range of parameters.     

Photoproduction of the Charged Top-Pions at the LHeC

The top triangle moose (TTM) model, which can be seen as the deconstructed version of the topcolor-assisted technicolor (TC2) model, predicts the existence of the charged top-pions π_t^± in low energy spectrum. In the context of this model, we consider photoproduction of π_t^± via the subprocesses γb → tπ_t^- and γb → tπ_t⁺ at the large hadron-electron collider (LHeC), in which high energy photon beams are generated by using the Compton backscatting method. We find that, as long as the charged top-pions are not too heavy, they can be abundantly produced via γb collision.     

人工色动力学对Wb耦合的修正

考虑了一代人工色（ＯＧＴＣ）模型和ｔｏｐｃｏｌｏｒ援助的多标度人工色（ＴＯＰＣＭＴＣ）模型中的规范玻色子对Ｗｔｂ耦合的贡献。发现对角ＥＴＣ玻色子的交换对Ｗｔｂ耦合没有直接贡献，运用ＬＥＰ给出的Ｒｂ的数值，发现对于一定范围内的参数值来说，ＯＧＴＣ模型中的ＥＴＣ规范玻色子交换和ＴＯＰＣＭＴＣ模型中的ＥＴＣ规范玻色子交换和ｃｏｌｏｒｎ交换对ＣＫＭ矩阵元Ｖｔｂ的贡献都是相当大的，Ｖｔｂ可能被费米实验室ＴｅｖａｔｒｏｎＲｕｎ３探测到。