随机非球形粒子全极化散射的时间相关Mueller矩阵解

从与时间相关的矢量辐射传输方程推导一阶Mueller矩阵解,用来模拟Gauss型平面脉冲波入射下,一层随机、非均匀取向非球形粒子的全极化双站散射.数值计算了同极化和去极化脉冲响应,与入射脉冲进行了比较,说明了随机介质的物理参数,如粒子的取向和占空比、入射角、极化以及层厚等对脉冲响应的影响 关键词： 平面脉冲波 非球形粒子 Mueller矩阵     

重离子碰撞中的矢量介子自旋排列

在非对心相对论重离子碰撞中,参与反应的系统具有巨大的轨道角动量,从而使产生的夸克胶子等离子体具有极强涡旋场,并通过自旋-轨道相互作用导致部分子的自旋极化,经过强子化导致重子的自旋极化以及矢量介子的自旋排列等可观测效应.矢量介子的自旋排列是指其自旋密度矩阵的00元素ρ00偏离1/3.在矢量介子衰变到两个赝标介子的过程中,衰变产物的极角分布只与ρ00有关,以此可以对自旋排列进行测量.理论研究表明,重离子碰撞过程中,重子的自旋极化反映了夸克自旋极化的时空平均效应,而矢量介子自旋排列则反映了夸克反夸克自旋极化的局域相空间关联.本文回顾了相对论重离子碰撞中矢量介子自旋排列的相关理论工作.重点以非相对论夸克融合模型为例,明确地计入夸克极化的相空间依赖性,展示了矢量介子自旋排列与夸克反夸克自旋极化特别是它们之间相空间关联的关系.本文还讨论了涡旋、电磁场、有效φ介子场以及它们的局域涨落对φ介子自旋排列的贡献,结果显示强作用场的时空关联效应是导致φ介子自旋排列的主要因素.矢量介子自旋排列为探索强相互作用物质和强相互作用场的性质提供了新途径.     

机载C波段全极化SAR海面风矢量反演理论研究及实验验证

机载全极化SAR海面风矢量反演研究对于近海岸复杂气象条件下风矢量探测具有重要意义. 本文从极化散射理论出发,通过分析全极化SAR探测数据与海面风矢量的关系, 设计了全极化SAR海面风矢量反演方案.依据机载SAR高机动性和全极化两个探测特点, 针对VV极化探测数据,提出了基于最大似然估计的海面风矢量反演方法,并设计了飞行实验方案; 针对VH极化探测数据,提出了通过带约束最优拟合的VH极化海面散射模型反演风速, 再利用CMOD5地球物理模型函数计算风向的海面风矢量反演方法. 利用机载全极化SAR探测的台风'海葵'边缘数据,开展了海面风矢量反演实验研究. 研究结果表明,两种风矢量反演方法均可不借助辅助信息,反演复杂气象条件下的海面风矢量. 前者反演风向、风速的均方根误差分别为18.0°, 1.8 m/s, 后者反演风向、风速的均方根误差分别为9.3°, 1.2 m/s,后者的反演精度优于前者. 这是因为VH极化归一化雷达截面与风向和雷达入射角无关,仅与风速密切相关, 更适合复杂气象条件下的海面风矢量反演. 关键词： 机载全极化SAR 海面风矢量 理论研究 实验验证     

随机介质中的矢量辐射传输理论

本文讨论了极化电磁波在随机介质中多次散射,传输和热辐射的斯托克斯矢量的辐射传输理论。其中包括随机分布离散的球形和非球形粒子的矢量辐射传输方程,离散坐标-特征分析法,付利叶变换,迭代法等数值解。讨论了非球形粒子的穆勒矩阵。并研究了密集分布的散射粒子介质的辐射传输理论,考虑了密集粒子散射的相干性,计算了有效传播常数。理论及数值结果与实验作了很好的比较。     

随机介质中的矢量辐射传输理论

本文讨论了极化电磁波在随机介质中多次散射，传输和热辐射的斯托克斯矢量的辐射传输理论。其中包括随机分布离散的球形和非球形粒子的矢量辐射传输方程，离散坐标——特征分析法，付利叶变换，迭代法等数值解。讨论了非球形粒子的穆勒矩阵。并研究了密集分布的散射粒子介质的辐射传输理论，考虑了密集粒子散射的相干性，计算了有效传播常数。理论及数值结果与实验用了很好的比较。     

电磁介质的极化和磁化

采用矢量分析方法,我们建立了电磁介质极化和磁化的一般理论,恰当地定义了可以描述任意束缚电荷和束缚电流分布的极化强度矢量和磁化强度矢量.无需借助电偶极子模型和分子环流模型,仍然可以推导束缚电荷和束缚电流分布与极化强度矢量和磁化强度矢量的定量关系.在宏观电磁理论中,分子环流模型和磁偶极子模型具有同等的地位,它们都可以诠释自旋磁矩的磁效应.     

碰撞能对S(1D) +H2(v=0, j=0)→SH+H反应立体动力学性质的影响

利用1A′态的势能面[ Ho et al., J. Chem. Phys. 116, 4124 (2002)],采用准经典轨线方法研究了在不同碰撞能条件下,S(1D) +H2(v=0, j=0)→SH+H反应的立体动力学性质. 通过计算得到了描述反应物速度矢量k与产物的转动角动量矢量j′这两个矢量相关的分布函数P(r)、描述反应物速度矢量k、产物速度矢量k′与产物的转动角动量矢量j′这三个矢量相关的二面角分布函数P(r)以及描述反应产物角动量极化的分布函数P(r,r).计算结果表明产物的转动角动量矢量j′在空间具有明显的定向和取向效应,并且产物的转动角动量具有强烈的极化. 另外,计算结果还表明这些立体动力学性质对碰撞能非常敏感.     

一层随机非球形粒子高阶散射矢量辐射传输迭代解的参数求逆

根据一层随机非球形粒子矢量辐射传输(VRT)方程的一阶与高阶Mueller矩阵解的差异,提出了在已知一些参数的条件下,用水平与垂直同极化和交叉极化后向散射测量反演非球形粒子复介电常数和单位面积粒子数的迭代方法,并用极化后向散射强度的模拟测量数据及机载合成孔径雷达(Air SAR)实测数据进行了反演试验,并对反演值与各参数的关系以及测量噪声对反演的影响进行了讨论.     

碰撞能对S(1D) +H2(v=0, j=0)→SH+H反应立体动力学性质的影响

利用1A′态的势能面[ Ho et al., J. Chem. Phys. 116, 4124 (2002)]，采用准经典轨线方法研究了在不同碰撞能条件下，S(1D) +H2(v=0, j=0)→SH+H反应的立体动力学性质. 通过计算得到了描述反应物速度矢量k与产物的转动角动量矢量j′这两个矢量相关的分布函数P(r)、描述反应物速度矢量k、产物速度矢量k′与产物的转动角动量矢量j′这三个矢量相关的二面角分布函数P(r)以及描述反应产物角动量极化的分布函数P(r,r).计算结果表明产物的转动角动量矢量j′在空间具有明显的定向和取向效应，并且产物的转动角动量具有强烈的极化. 另外，计算结果还表明这些立体动力学性质对碰撞能非常敏感.     

重离子碰撞中QCD物质整体极化的实验测量

高能重离子碰撞中Λ超子和φ, K^*0矢量介子的整体极化的实验数据证实了夸克物质整体极化的新现象,引起了研究人员的广泛关注,成为高能核物理前沿新的热点研究方向.本文主要从实验测量上回顾整体极化研究,着重阐述相对论重离子对撞机(RHIC)上的螺旋径迹探测器(STAR)合作组在不同对撞能量点开展的Λ超子和φ, K^*0介子的整体极化测量结果,并拓展到含有多个奇异夸克粒子Ξ,Ω的整体极化测量和Λ沿着束流方向的局域极化研究.本文也将简单点评大型强子对撞机(LHC)能区和HADES实验低能区的测量结果,并对这些实验结果给出的物理信息进行简单描述.     

Neutralinos in E_{6} inspired supersymmetric U(1)' models

The neutralino sector in inspired supersymmetric models with extra neutral gauge bosons and singlet Higgs fields contains additional gaugino and singlino states compared to the MSSM. We discuss the neutralino mixing in rank-5 and rank-6 models and analyze the supersymmetric parameter space where the light neutralinos have mainly singlino or MSSM character. The neutralino character, resonance effects of the new gauge bosons and, assuming mSUGRA-type RGEs, different selectron masses lead to significant differences between the MSSM and the extended models in neutralino production at an linear collider. Beam polarization may improve the signatures to distinguish between the models. In an appendix, we present the mass terms of the gauge bosons, charginos and sfermions which show a significant different mass spectrum than in the MSSM and give all relevant neutralino couplings. Received: 17 July 2001 / Revised version: 21 November 2001 / Published online: 25 January 2002     

Supersymmetry and polarization in e+e− collisions (II). Fermionic partners of the gauge bosons

We study the pair production of fermionic partners of the gauge bosons in e⁺e^? collisions with polarized beams. We calculate the cross sections and the spin asymmetries for various processes using different models for the basic properties of gauginos. If they exist and if they are rather light, they should be discovered in future e⁺e^? colliders. We show that polarization provides very special signatures for their experimental search.     

Universality in weak interactions—The cabibbo suppression

An SU₃ gauge model of weak interactions, which generates the Cabibbo suppression spontaneously and consistently, is presented. Out of the eight currents, a triplet couples to relatively light gauge bosons and satisfies the commutation relations of the SU₂-universality algebra of Gell-Mann. The other five couple to necessarily very massive gauge bosons. The leptons have a realistic mass spectrum and the (bare) quarks are massless. The theory as it stands does not encompass charm and cannot suppress strangeness changing neutral currents; both these deficiencies require a larger gauge group for their correction.     

Higher level string resonances in four dimensions

We study higher level Regge resonances of open superstrings, focusing on the universal part of the Neveu-Schwarz sector common to all D-brane realizations of the standard model. For Regge states with masses far above the fundamental string scale, we discuss the spin-dependence of their decay rates into massless gauge bosons. Extending our previous work on lowest level string excitations, we study the second mass level at which spins range from 0 to 3. We construct the respective vertex operators and compute the amplitudes involving one massive particle and two or three gauge bosons. To illustrate the use of Britto-Cachazo-Feng-Witten (BCFW) recursion relations in superstring theory, we build the four-gluon amplitude from on-shell amplitudes involving string resonances and gauge bosons.     

Top Quark Pair Production at e^＋e^— Colliders in the Topcolor—Assisted Technicolor Model

In the framework of topcolor-assisted technicolor model we calculate the contributions from the preudo Goldstone bosons and new gauge bosons to e^ e^-→ttk.We find that for reasonable ranges of the parameters,the preudo Goldstone bosons afford dominate contribution,the correction arising from new gauge bosons is negligibly small,the maximum of the relative corrections is-10% with the center-of-mass energy √s=500GeV;whereas in the case of √s=1500 GeV,the relative corrections could be up to 16%.Thus large new physics might be observable at the experiments of next-generation linear colliders.     

Search for new neutral gauge bosons at LHC

New heavy gauge bosons belonging to an extended (in relation to the Standard Model) gauge sector are present in Grand Unified Theories, as well as in a number of models aimed at solving the hierarchy problem—in particular, in the technicolor model and in some versions of multidimensional field theories (for example, in the Little Higgs model). The LHC potential for seeking new neutral gauge bosons in decays to two muons is studied.     

Relations between the masses of the superpartners of leptons and quarks,the goldstino coupling and the neutral currents

The mass² splittings between leptons and quarks and their spin-0 partners under supersymmetry are related to the goldstino couplings. The bosonic partner of the goldstino cannot be the photon itself. But it should be, in part, a linear combination of the various neutral gauge bosons. As a result, mass relations constrain the neutral current structure of the theory. They require the existence of at least two neutral gauge bosons in addition to the photon and suggest the possibility of a universal mass² splitting between leptons and quarks and their spin-0 partners.     

Scalar lattice gauge theory

Scalar lattice gauge theories are models for scalar fields with local gauge symmetries. No fundamental gauge fields, or link variables in a lattice regularization, are introduced. The latter rather emerge as collective excitations composed from scalars. For suitable parameters scalar lattice gauge theories lead to confinement, with all continuum observables identical to usual lattice gauge theories. These models or their fermionic counterpart may be helpful for a realization of gauge theories by ultracold atoms. We conclude that the gauge bosons of the standard model of particle physics can arise as collective fields within models formulated for other “fundamental” degrees of freedom.     

Gauge bosons at zero and finite temperature

Gauge theories of the Yang–Mills type are the single most important building block of the standard model of particle physics and beyond. They are an integral part of the strong and weak interactions, and in their Abelian version of electromagnetism. Since Yang–Mills theories are gauge theories their elementary particles, the gauge bosons, cannot be described without fixing a gauge. Therefore, to obtain their properties a quantized and gauge-fixed setting is necessary.     

Some issues in a gauge model of unparticles

We address in a recent gauge model of unparticles the issues that are important for consistency of a gauge theory, i.e., unitarity and the Ward identity of the physical amplitudes. We find that non-integrable singularities arise in physical quantities like the cross section and the decay rate from the gauge interactions of unparticles. We also show that the Ward identity is violated due to the lack of a dispersion relation for charged unparticles although the Ward–Takahashi identity for general Green functions is incorporated in the model. A previous observation that the contribution of the unparticle (with scaling dimension d) to the gauge boson self-energy is a factor (2−d) of the particle’s self-energy has been extended to the Green function of triple gauge bosons. This (2−d) rule may be generally true for Green functions for any number of points of the gauge bosons. This implies that the model would be trivial even as one that mimics certain dynamical effects on gauge bosons in which unparticles serve as an interpolating field.