手征QCD_2模型的有效拉氏量和质量生成

利用路径积分方法,研究了(1+1)维带γ_5耦合的规范理论。通过进行一非阿贝耳手征变量变换和选择更一般的正规化算子,精确解出了费密子行列式,证明了理论中可以存在玻色子的质量生成机制。除了一质量项外,得到的解也包含有一规范化的Wess-Zumino-Witten反常作用量泛函和一些别的非定域项。     

DTO分子反应碰撞的非对称性

基于DTO分子（X¹A₁）的氢同位素效应,得到修正的Born-Oppenheimer（B-O）理论下多体展式分析势能函数.用准经典的Monte-Carlo轨迹法研究了O+DT（0,0）的分子反应动力学过程.结果表明：在碰撞能量较低时（<209.2?kJ·mol^-1）,O+DT（0,0）可以生成长寿命络合物DTO（X¹A₁）,并且该络合反应是无阈能的,这一结论与多体项展式理论计算的DTO分子势能曲线结果一致.碰撞能大于209·2?kJ·mol^-1时,逐渐出现置换产物TO和DO,随碰撞能进一步增大,分子将被完全碰散成D,T,O原子.反应O+DT（0,0）→OD+T和O+DT（0,0）→OT+D是有阈能的反应,置换产物TO和DO轨线存在非对称性. 关键词： DTO 势能函数 分子反应碰撞 轨线非对称性     

轻原子核中的超流效应

本文用Боголюбов‐Беляев理论讨论了轻核中(F¹⁹-Mg²⁴)对偶力对转动惯量及奇偶质量差的影响。取平均对偶力强度G为GA～16—18MeV时(相应能隙△≈1.5MeV),可以很好地解释它们的转动惯量。我们估计了奇偶质量差,结果和实验相近,在轻核中它比能隙△要略大些,计算表明粒子数涨落△N～1—1.5。我们还讨论了理论中忽略的高级项的修正以及理论的主要困难。 关键词：     

强光场中电子系统与多光子的相互作用

在非相对论量子场论框架下,给出电子场和光子场相互作用时整个系统的哈密顿量H_tot,研究在强光场中非线性项即A²项的作用.电子系统用Fermi-Dirac统计的Schr?dinger量子波场描述.采用“自洽平均场”和“有效质量”近似,并基于位移谐振子的相干态方法,得到电子波光量子场算子函数的Lee-Low-Pines表式f(b⁺),再利用算子函数f(b⁺)对算子b+的微商公式,导出了相关理论计算公式,其中包括电子能量E< 关键词： 强光场 多光子 非线性光学     

InnoSlab混合腔输出光束质量的理论研究

对InnoSlab Laser用混合腔的输出光束质量问题从热透镜效应和腔镜的不对准两个方面的影响进行理论分析,并从远场光强分布、远场发散角、光腰半径、光束质量因子M²值和桶中功率曲线等几个角度进行了讨论,特别是离轴非稳腔方向上腔镜倾斜对光束质量的影响,利用M²值和PIB曲线两个参数共同评价非稳腔的光束质量,对目前并无统一标准的非稳腔光束质量评价问题提供了有意义的参考. 关键词： InnoSlab 混合腔 光束质量 桶中功率     

Breit夸克势的不同次正规化与ηc-J/ψ等的质量劈裂

用夸克势模型研究结构相同而自旋和轨道量子数不同的介子之间质量劈裂是检验势模型有效性的重要手段之一. 在以往的用各种夸克势模型计算质量劈裂工作中, 当轻介子和重介子一起计算时, π-ρ很容易劈裂, 而η_c-J/ψ等的劈裂都很 难达到实验值. 这里首先用正规化形状因子μ²/(q²+μ²), 对完整的动量空间中的Breit夸克势的第三项实施二次正规化, 除了第一项 库仑势和第七项常数项势, 对其余的项实施一次正规化, 然后用来计算 质量劈裂. 研究计算发现, 只有当屏蔽质量μ取为关于 折合质量μ_r=m_r m_j/(m_r+m_j) 的三阶多项式时, 轻介子π-ρ和重介子η_c-J/ψ, η_b-Υ(1s), 还有χ_c0-χ_c1-χ_c2 等的劈裂 精确达到实验值, 同时其他介子质量也都比以往得到较大的改善. 因此, 本文给出了一个有效的夸克势模型.     

C-H 键和C-C 键核自旋偶合常数的理论研究

利用PM3级别最大重迭对称性分子轨道法和最大键级杂化轨道方法,计算了系列烃类化合物的杂化轨道和电荷分布,拟合出计算C-H及C-C偶合常数的简单关系式. 研究了各种烃类分子中不同的C-H键和C-C键偶合常数,理论计算值和实验数据都较为符合. 进一步验证了直接键连¹J_CX偶合常数主要取决于偶合作用中的Fermi接触项,为从简单价键理论角度解释和计算¹J_CH和¹J_CC提供了一种简便直观的方法.     

SiF$lt;sub$gt;2$lt;/sub$gt;基态分子的结构与势能函数

运用Gaussian03软件包,采用密度泛函理论中的B3P86 方法,结合6-311++G^**（3df,3pd） 基组对基态SiF₂分子的平衡电子结构和谐振频率进行了优化计算,得到了其稳定结构为C_2v构型.SiF₂基态电子态为X¹A₁,平衡核间距R_Si—F=0.1061　nm,键角α_F—Si—F=100.6762°,离解能D_e=13.8　eV.应用多体项展式理论推导了基态SiF₂分子的解析势能函数,其等值势能图准确地再现了SiF₂分子的平衡构型特征和能量变化. 关键词： 2')" href="#">SiF₂ Murrell-Sorbie函数 多体项展式理论     

类锂体系(Z=21—30)基态1s22s电离能和相对论项能的理论计算

使用全实加关联方法和里兹(Ritz)变分方法计算了类锂体系(Z=21—30)基态1s²2s的非相对论能量和波函数；包括动能修正、电子-电子接触项、轨道-轨道相互作用项以及Darwin项的相对论修正和质量极化项由全实加关联波函数的一阶微扰给出，量子电动力学修正QED(quantum electronic dynamic)由有效核电荷方法和类氢公式计算；给出了中等核电荷的高电离类锂体系基态的电离能、相对论效应的项能(term energy)，并将计算结果与实验数据进行了比较，表明FCPC 关键词： 类锂体系 全实加关联 电离能 项能     

厄米-高斯光束的M2因子矩阵

提出了厄米-高斯光场的M²因子矩阵.引入束半宽平方的交叉项、M²因子的交叉项,理论推导出了在同一坐标系下光场旋转一定角度后的M²因子矩阵,数值模拟了与M²因子矩阵有关的各参数随光场旋转角度变化的规律,给出了光场的M²因子矢量点随光场旋转角度变化的轨迹曲线.计算结果与理论推导结果相符,证实了利用M²因子矩阵可以将旋转前后的二维厄米-高斯光场用旋转矩阵统一起来.该方法可推广到对一般的二维高阶高斯光束的光束质量的理论分析上,具有普适性,对光束质量的实际测量有重要的理论指导意义. 关键词： M²因子矩阵')" href="#">M²因子矩阵 厄米-高斯光束 非对称激光束 矩阵光学     

Baryon masses,chiral extrapolations,and all that<Superscript>⋆</Superscript>

We calculate the baryon octet masses to fourth order in chiral perturbation theory employing dimensional and cut-off regularization. We analyze the pion and kaon mass dependences of the baryon masses based on the MILC data. We show that chiral perturbation theory gives stable chiral extrapolation functions for pion (kaon) masses below 550 (600) MeV. For the pion-nucleon sigma term we find (0) = 39.5...46.7MeV.     

Anomalous Vector-Boson Mass Generation on a Lattice

We show the vector boson mass generation on a lattice with the Wilson's fermion formulation. By calculating explicitly the change of the effective action under chiral transformation, it is also found an arbitrariness in the solution of the chiral Schwinger model, which depends on a lattice regularization in continuum theory.     

Strong isospin breaking of the nucleon and delta masses on the lattice

Strong isospin breaking in the spectrum of the nucleons and deltas can be studied in lattice QCD with the help of chiral perturbation theory. At leading order in the chiral expansion, the mass splittings between the proton and neutron and between the deltas are linear in the quark mass difference. The next-to-leading order contributions to these splittings vanish even away from the strong-isospin limit. Therefore, any non-linear quark mass dependence of these mass splittings is a signal of the next-to-next-to-leading order mass contributions, thus providing access to low energy constants at this order. We determine the mass splittings of the nucleons and deltas in two-flavor, heavy baryon chiral perturbation theory to next-to-next-to-leading order. We also derive expressions for the nucleon and delta masses in partially quenched chiral perturbation theory to the same order. The resulting mass expressions will be useful both for the extrapolation of lattice data on baryon masses, and for the study of strong isospin breaking.     

QCD with two colors at finite baryon density at next-to-leading order

We study QCD with two colors and quarks in the fundamental representation at finite baryon density in the limit of light-quark masses. In this limit the free energy of this theory reduces to the free energy of a chiral Lagrangian which is based on the symmetries of the microscopic theory. In earlier work this Lagrangian was analyzed at the mean-field level and a phase transition to a phase of condensed diquarks was found at a chemical potential of half the diquark mass (which is equal to the pion mass). In this article we analyze this theory at next-to-leading order in chiral perturbation theory. We show that the theory is renormalizable and calculate the next-to-leading order free energy in both phases of the theory. By deriving a Landau–Ginzburg theory for the order parameter we show that the finite one-loop contribution and the next-to-leading order terms in the chiral Lagrangian do not qualitatively change the phase transition. In particular, the critical chemical potential is equal to half the next-to-leading order pion mass, and the phase transition is of second order.     

矢引力子场度规场引力理论的共形平直静止解及引力场的能量动量赝张量的正常性

本文求出了VGM引力理论的共形平直静止解。文中把胡宁表达式引入VGM,它同样是守恒的能量动量表达式。对于单个集中质量的引力场,与GR一样,可证实引力质量与惯性质量相等。但Einstein的等效原理在这理论中并不成立。利用所求得的解,可知当n<1/4时,引力场的能量动量赝张量就是正常的。 关键词：     

Electromagnetic low-energy constants in χPT

We investigate three-flavour chiral perturbation theory including virtual photons in the limit in which the strange quark mass is much larger than the external momenta and the up and down quark masses, and where the external fields are those of two-flavour chiral perturbation theory. In particular, we work out the strange quark mass dependence of the electromagnetic two-flavour low-energy constants C and k_i. We expect that these relations will be useful for a more precise determination of the electromagnetic low-energy constants. PACS 11.30.Rd; 12.39.Fe; 13.40.Dk; 13.40.Ks     

Pion-kaon scattering near the threshold in chiral SU(2) perturbation theory

In the context of chiral SU(2) perturbation theory, pion-kaon scattering is analysed near the threshold to fourth chiral order. The scattering amplitude is calculated both in the relativistic framework and by using an approach similar to heavy baryon chiral perturbation theory. Both methods lead to equivalent results. We obtain relations between threshold parameters, valid to fourth chiral order, where all those combinations of low-energy constants which are not associated with chiral-symmetry breaking terms drop out. The remaining low-energy constants can be estimated using chiral SU(3) symmetry. Unfortunately, the experimental information is not precise enough to test our low-energy theorems.     

Proof of Chiral Symmetry Breaking and Persistent Mass Condition in Vector- Like Gauge Theory

We give the details of rigorous proof of some mass inequalitiee in a vector-like gauge theory based on any simple group G. These mass inequalitiee lead to the conclusions that in auch a theory the chiral symmetries associated with all G representations of quarks must be spontaneously broken, and the persistent mass condition ie justified for any composite particles when the vacuum angle is zero or massless quarks exist.     

Baryon masses in large N c chiral perturbation theory

We analyse the baryon mass spectrum in a framework which combines the 1/N _c expansion with chiral perturbation theory. Meson loop contributions involving the full SU(3) octet of pseudoscalar Goldstone bosons are evaluated, and the influence of explicit chiral and flavor symmetry breaking by non-zero and unequal quark masses is investigated. We also discuss sigma terms and the strangeness contribution to the nucleon mass. Received: 29 June 1998 / Revised version: 25 November 1998