Study on effective masses of meson in dense nuclear matter

We introduce and summary our research progress on the effective masses of K meson in dense nuclear matter.     

Isoscaling Parameter α as a Possible Probe of Medium Effect of Nucleon--Nucleon Cross Section

The medium effect of nucleon-nucleon cross section reed σ^medNN （αm） on the isoscaling parameter α is investigated for two central nuclear reactions ^40 Ca＋ ^40Ca, ^60Ca＋^60Ca within isospin-dependent quantum molecular dynamics at beam energies from 40 to 50 MeV/nucleon. It is found that there is the very obvious medium effects of nucleonreed nucleon cross section σ^medNN （αm） on the isoscaling parameters a. In this case the isoscaling parameter a is a possible probe of the medium effect of nucleon-nucleon cross section σ^medNN （αm） in the heavy ion collisions. The mechanism of the above-mentioned properties is studied and discussed.     

夸克-介子耦合模型

对夸克-介子耦合模型的研究进展及现状进行了简述.在此基础上,利用非拓扑孤子袋模型的思想和改进的夸克质量密度相关(IQMDD)模型,考虑夸克之间的排斥作用而加入ω介子,称为IQMDD-Ⅰ模型,得到了基态波函数和介子场满足的方程.利用平均场近似方法,通过得到的基态夸克波函数计算了核子的均方根半径和磁矩等可观测量,其结果与实验值吻合得较好.     

△-Resonance Effective Mass in Medium

Based on the relativistic chiral effective field theory, we study the effective mass of the △-resonance in medium by investigating the self-energy of the △-resonance related to the πN decay channel in symmetric nuclear matter. We find that the effective mass of △-resonance decreases evidently with increasing nuclear density p. In our calculation, we also consider the influence of the shifts of the nucleon mass, pion mass and its decay constant due to the restoration of chiral symmetry in medium. The results are roughly consistent with the data given by Lawrence Berkeley National Laboratory.     

与额外维相关的膜宇宙模型

对引力场的能量\|动量和角动量守恒定律研究进展进行了总结。依此探讨了一般五维时空膜宇宙模型中的能量\|动量张量、 角动量张量以及它们的守恒定律。通过计算一个膜宇宙模型中的能动张量, 论证了该模型中“可见膜”上的引力非常弱, 这可认为是从引力的角度反映了规范层次问题。结果与一般的结论, 即引力系统总能量为零是一致的。同时, 分析了这个膜宇宙模型中的角动量张量, 计算了该模型中的总角动量, 讨论了暴涨Randall\|Sundren(RS)模型中的总角动量的一些性质。说明了在这类模型中总角动量的类空分量均为零, 这与普通RS模型是一样的。同时, 分析了RS模型中背景以及膜上的宇宙学常数, 发现在RS模型中五维背景宇宙学常数和两个膜上的真空能都能取它们的自然值。最后通过修改RS模型, 得到了一种可以产生很小的有效宇宙学常数的机制。We summarized both the general covariant energy\|momentum and angular momentum conservation law in the gravitational system and analyzed the general covariant energy\|momentum tensor of the gravitational system in general five\|dimensional cosmological in brane\|universe models. After calculating this energy\|momentum for the cosmological generalization of the Randall\|Sundrum(RS) model which includes the original RS model as the static limit, we are able to show that the weakness of the gravitation on the “visible” brane is a general feature of this model. This is the origin of the gauge hierarchy from a gravitational point of view. Our results are also consistent with the fact that a gravitational system has vanishing total energy. We also discussed the properties of the general covariant angular momentum in five\|dimensional brane-universe model. With calculation of the total angular momentum of this model, we analyzed the properties of the total angular momentum in the inflationary RS model. We pointed that the space-like components of the total angular momentum are zero while the others are non-zero, which agrees with the results from ordinary RS model. We also investigated the bulk cosmological constant and brane vacuum energies in RS model. We show that the five\|dimensional bulk cosmological constant and the vacuum energies of the two branes could take their natural values. Finally we argued how we can generate a small four-dimensional effective cosmological constant on the branes by modifying the original RS model.     

二维可积系统的求迹公式和周期轨道的量子化

从Berry–Tabor求迹公式出发,导出了二维可积系统周期轨道作用量的半经典量子化条件.利用此量子化条件,考虑周期轨道满足的周期条件,得到了二维无关联四次振子系统周期轨道作用量的半经典量子化条件,并给出了半经典能级公式.对能级与周期轨道的对应关系做了分析.     

单核子在具有八极形变的平均势场中的混沌运动(Ⅲ)初始相干态空时演化中几率密度及扰动强度的研究

运用在二维不对称谐振子势加八极形变势中传播的二维不对称谐振子相干态,研究了不同强度耦合作用下密度矩阵的复杂性及对干扰动强度微小变动的敏感性。发现相应于对应经典系统作规则、部分混沌、及整体混沌运动的相空间区域,量子系统有对应的特征性的表现,它们与势能面上负曲率的存在及负曲率的大小有关系.     

SU(2)Chern-Simons涡旋解的拓扑结构

运用规范势分解理论研究了 Dunne Jackiw Pi Trugenberger 模型中的自对偶方程, 得到一个静态的自对偶Chern Simons多涡旋解, 每个涡旋由5个参数描述。 发现了自对偶解与拓扑数之间的关系, 而拓扑数由Brouwer度与Hopf指标确定。 同时, 也研究了该涡旋解的磁通量的拓扑量子化。The self dual equation and its solution in SU(2) Dunne Jackiw Pi Trugenberger model has Been discussed with special ansatz for the Lie algebraic structures of su(2) and gauge potential decomposition. We obtainer a new concrete self dual equation and found the relationship between SU(2) Chern Simons vortices and topological number which is determined by Hopf indices and Brouwer degrees of  mapping. (two positions, one scale, one phase per vortex and one charge of each vortex) m vortices solutions are discribed by using 5m parameters. The quantization of flux is also studied in this case.     

在pA碰撞中K~±,η和ф介子的阈下产生

简要评述了在pA碰撞过程中K±,η和ф介子的阈下产生及其对应的物理含义。这些介子的阈下产生都可以在兰州CSR上实现,特别是通过pA碰撞实现ф介子的阈下产生还没有看到实验数据的报道。