分支比Rb的测量值对最小Higgs模型的约束

系统研究了最小Higgs(LH)模型预言的所有新粒子对Z→bb过程分支比R_b的量子修正. 结果表明此修正主要来源于类矢量夸克T、规范玻色子Z_H和B_H, 其数值对自由参数f, c'和x_L非常敏感.R_b的最新测量数据对这些参数有很强的限制.     

PG玻色子Pa0在Tevatron上的可能物理迹象

在Topcolor-Assisted Technicolor框架下,计算了多标度WTC模型的中性色八重态PG玻色子P0a对top夸克产生截面的修正,结果表明P0a可以增大Tevatron上top夸克的产生截面.     

Bd0→φK0极化反常和Bd→φKS CP不对称的研究

在模型Ⅲ下, 仅考虑来自于中性规范玻色子H⁰, h⁰和 A⁰产生的树图阶味改变中性流的贡献, 并利用QCD因子化方法, 对B_d⁰→φK^*0衰变过程的极化反常和 B_d→φK_S衰变过程的CP不对称进行了研究, 经过计算发现, 在147<|λ_bsλ_ss|<165的参数范围内, 这两个过程中存在的反常现象能够同时给予解释.     

一代Techniwlor模型对稀有衰变t→cV的贡献

计算了一代人工色(Technicolor)模型中的赝标哥尔斯通粒子对稀有衰变t→cV(V=Z、γ、g)的贡献.与标准模型的贡献相比,这种新的贡献提高了3—4个数量级.对适当的输入参数,一代Technicolor模型对t→cV分支比的贡献最大可达:B(t→cg)～10^－6,B(t→cZ)～10^－7,B(t→cγ)～10^－5.     

具有T宇称的最小Higgs模型与LHC上Higgs波色子与弱规范波色子的联合产生

Considering the process pp→VH ＋X（V = W or Z） is a significant channel for searching for a light Higgs boson, we calculate the contributions of the littlest Higgs model with T-parity （called LHT model） to its production cross section. We find that, in most of the parameter space, the value of the relative correction parameter R is very small. However, with reasonable values of the free parameters, its value can be significantly larger.     

LH模型与高能e+e-对撞机上ZH的产生

在最小Higgs模型(LH)框架内讨论了Higgs粒子产生过程e⁺e^-→ZH.结果表明,对该过程的修正效应主要来自重光子A′,但如果自由参数c取值范围为0.85—1,则重规范玻色子Z′的贡献就不能忽略.在LH模型大部分参数空间内,过程e⁺e^-→ZH的总产生截面σtot与标准模型(SM)相应值的偏差大于5%,应该能在未来的高能e+e–对撞机(LC)实验中观测到     

小Higgs模型对顶夸克在eγ对撞机上产生的影响

在最小Higgs模型和T宇称下的最小Higgs模型中, 计算了单个顶夸克的产生 过程e^－γ→ν_ebt的产生截面, 并讨论了这两种模型对该过程产生截面的贡献. 发现在合适的参数范围内, 来自T宇称下的最小Higgs模型中对Wtb耦合的修正项对该过程产生截面的相对修正大于5%,这种影响能在将来的直线对撞机实验中探测到. 然而, 在最小Higgs模型中, 新的规范玻色子W±H对该过程的贡献非常小.     

B0d→φK*0极化反常和Bd→φKs CP不对称的研究

在模型Ⅲ下,仅考虑来自于中性规范玻色子H0,H0和A0产生的树图阶味改变中性流的贡献,并利用QCD因子化方法,对B0d→φK(≠)0衰变过程的极化反常和Bd→φKs衰变过程的CP不对称进行了研究,经过计算发现,在147＜|λbsλss|＜165的参数范围内,这两个过程中存在的反常现象能够同时给予解释.     

DES模型在压气机亚音转子中的应用探讨

本文运用分离涡模拟(DES)方法研究了不同工况下压气机亚音转子的流动情况,分析了其时均与瞬时流场中顶部间隙泄漏流动和根部角区的流动分离.通过与S-A模型计算结果的对比表明,DES模型在模拟顶部泄漏流动及二次泄漏、泄漏流在转子下游与尾迹的干涉时能够捕捉到更强的旋涡结构,在模拟转子根部角区的分离时也能获得更为丰富的流动现象.对不同工况的DES计算表明负荷的上升会使泄漏涡形成的位置向上游移动,从而导致并加剧二次流动,并对叶栅下游泄漏涡与尾迹的干涉产生影响.对设计工况下瞬时流场的分析表明,泄漏涡在叶栅下游体现出周期性的强弱变化,近叶根分离区也体现出明显的非定常性.     

一维湍流模型对He平面羽流和CH4/H2/N2射流火焰的数值模拟

本文采用一维湍流模型（ODT）对氦气平面羽流和CH₄/H₂/N₂射流火焰进行数值模拟,和前人的实验结果进行定量地对比。结果表明,ODT模型能够准确地预测平面羽流基本特征,湍流涡团的分布同流场拉伸率之间具有密切的关系,涡团强度的分布能够直观地表明当地的湍流强度。ODT模型埘CH₄/H₂/N₂瞬态火焰的模拟定性反应了火焰特性及其与湍流作用的规律,对温度-混合分数的预测值和实测值进行比较,发现甲烷火焰燃烧在富燃料侧并未达到平衡状态,因而基元反应对火焰特性的预测具有重要作用。     

The Lepton Flavor Violating Decays of AHin the Littlest Higgs Model with T-Parity Violation

The T-parity in the littlest Higgs model can be broken by the anomalous Wess-Zumino-Witten term, which leads that the lightest T-odd gauge boson A_H decays into the SM particles. First, we examine some lepton flavor violating decays of A_H, namely A_H→τ^±μ^干, A_H→τ^±e^干, and A_H→μ^±e^干. We find that the branching ratios can reach 10^-7 for A_H→τ^±μ^干, 10^-8 for A_H→τ^±e^干, and 10^-8 for A_H→μ^±e^干. Then, we study the lepton flavor violating plus jets signatures of the heavy charged gauge boson and mirror quarks at the LHC, and find that it is possible to be detected for pp→q_Hq_H→τ^±μ^干+4 jets, and hardly to be detected for pp→q_Hq_H→τ^±e^干(μ^±e^干)+4 jets and pp→ W_HW_H→τ^±μ^干(τ^±e^干, μ^±e^干)+6 jets.     

Littlest Higgs Model and Higgs Boson Associated Production with Top Quark Pair at High Energy Linear e+e- Collider

In the parameter space allowed by the electroweak precision measurement data, we consider the contributions of the new particles predicted by the littlest Higgs model to the Higgs boson associated production with top quark pair in the future high energy linear e⁺e^- collider (ILC). We find that the contributions mainly come from the new gauge bosons Z_H and B_H. For reasonable values of the free parameters, the absolute value of the relative correction parameter δσ/σ^SM can be significanly large, which might be observed in the future ILC experiment with √{S}=800 GeV.     

Flavor Changing Top Quark Decay and Bottom-Strange Production in the Littlest Higgs Model with T-parity

Flavor changing effects on the processes t → ch, e+e- → bs, e+e-→ bsh and pp → bs in the LHT model are investigated in this paper. We calculate the one-loop level contributions from the T-parity odd mirror fermions and gauge bosons. The results show that the top quark rare decay t → ch in the LHT model can be significantly enhanced relative to that in the SM. The bs production at linear colliders in the LHT model can enhance the SM cross section a lot and reach 0.1 fb in some parameter space allowed in the experiment. But the heavy gauge boson and mirror fermion loops have small contribution to the processes pp → bs and e+e-→ bsh. So the LHT effect on e+e-→ bs might be detected at future linear colliders, while it is too small to be seen for the e+e-→ bsh and pp → bs processes at future linear colliders and LHC.     

Muon g - 2 in the Littlest Higgs Model

In this paper the anomalous magnetic dipole moment of muon in the littlest Higgs (LH) model is studied at one-loop level. We discuss the dependence of the contributions on the global symmetry breaking scale f, mixing angles c and cˊ, and the Higgs triplet vacuum expectation value vˊ in the electroweak precision data preferring ranges. We find that the LH model can give a relatively small, but non-negligible extra weak contribution to the muon anomalous magnetic moment and can reduce the deviation of Δa_μ from 2.6σ for the SM to 2.5σ for the LH model.     

The Top-Charm Associated Production Within the R-Parity Violating Supersymmetric Model in Photon-Proton Collisions

The top-charm associated production with the effects from both B- and L-violating interactions in TeVscale photon-proton collisions is investigated in the framework of Rp minimal supersymmetric standard model. Withinthe bounds on the relevant R-parity violating couplings, the total cross section will reach the order of 10 fb in some partsof the parameter space.     

Top Quark Chromomagnetic Dipole Moment in the Littlest Higgs Model with T-Parity

The littlest Higgs model with T-parity, which is called LHT model, predicts the existence of the new particles, such as heavy top quarks, heavy gauge bosons, and mirror fermions. We calculate the one-loop contributions of these new particles to the top quark chromomagnetic dipole moment (CMDM) ΔK. We find that the contribution of the LHT model is one order of magnitude smaller than the standard model prediction value.     

Top Quark Chromomagnetic Dipole Moment in the Littlest Higgs Model with T-Parity

The littlest Higgs model with T-parity, which is called LHT model, predicts the existence of the new particles, such as heavy top quarks, heavy gauge bosons, and mirror fermions. We calculate the one-loop contributions of these new particles to the top quark ehromomagnetic dipole moment （CMDM） AK. We find that the contribution of the LHT model is one order of magnitude smaller than the standard model prediction value.