一级微扰QCD耦合的夸克物质体粘滞系数

在高密情况下考虑了夸克间弱的耦合,直接应用微扰计算得到的热力学势计算了奇异夸克物质(SQM)的体粘滞系数,发现介质效应使SQM的粘滞性提高2个量级左右     

准粒子描述下奇异夸克物质自洽热力学及对奇异星物态的影响

考虑夸克粒子间相互作用,研究了在准粒子近似下奇异夸克物质系统的热力学,发现由于热力学自洽的要求,需要在热力学势中额外增加一项.利用这一等效热力学讨论奇异夸克物质的物态方程及声速,得到了一个“软化”的物态,这与质量–密度相关模型是一致的.但准粒子描述模型能够显示介质效应对强相互作用耦合常数的依赖.     

奇异物质体黏滞系数的计算和奇异星振动的阻尼

利用与奇异夸克质量相关的非轻子弱过程u+s←→d+u的反应速率, 在考虑了夸克之间的相互作用并做了热力学自恰处理后, 重新推导、计算了奇异夸克物质的体黏滞系数. 由于热力学自恰的需要引入一项压力附加项, 使得奇异星的体黏滞系数比前人计算的有了很大的增加. 通过计算振动衰减时间我们发现, 虽然体黏滞系数增大了很多, 但以前对于奇异星观测的结论仍然成立.     

有限温度奇异夸克物质

本文简要介绍了近年来有限温度下奇异夸克物质的研究,包括早期宇宙中大块奇异夸克物质的研究;基于ＭＩＴ袋模型的ｓｔｒａｎｇｅｌｅｔ研究,以及运用质量密度相关模型对奇异夸克物质的研究,最后简略评述了关于奇异夸克物质性质的近期研究进展     

有限温度奇异夸克物质

本文简要介绍了近年来有限温度下奇异夸克物质的研究,包括早期宇宙中大块奇异夸克物质的研究;基于ＭＩＴ袋模型的ｓｔｒａｎｇｅｌｅｔ研究,以及运用质量密度相关模型对奇异夸克物质的研究,最后简略评述了关于奇异夸克物质性质的近期研究进展     

在极端相对论性原子核碰撞中奇异粒子的演化

在本文中我们用相对论流体力学方程描述了一个膨胀的夸克-胶子等离子体的演化.在此基础上考虑了相变和相变引起的温度效应后,用弛豫方程计算了不同初始温度的奇异粒子的时空分布以及总的奇异粒子数随时间的演化规律,分判定在极端相对论原子核碰撞中是否产生了夸克物质提供了一种理论依据.     

核子中奇异夸克分布不对称性与轻味夸克碎裂效应

核子中奇异－反奇异夸克分布的不对称性是核子结构研究中的重要非微扰效应, 然而至今未被实验所直接检验.为了探讨测量这种奇异分布不对称性的有效方法,考察了轻味夸克碎裂效应对测量奇异分布不对称性的影响.建议通过直接测量高能中微子和反中微子的带电流深度非弹散射中的带电和中性D介子的微分截面来测量奇异分布的不对称性.这种方法能够使奇异分布不对称性与轻味夸克碎裂的效应相分离.     

NuTeV反常与奇异夸克反夸克不对称性

总结了利用核子内的奇异夸克反奇异夸克不对称性来解释NuTeV反常的工作,表明奇异夸克反奇异夸克不对称性可作为解释NuTeV反常的一种合理机制,也说明了NuTeV反常现象也可能是对奇异夸克反奇异夸克不对称性的一种支持。This talk summarized the results of using strange quark-antistrage quark asymmetry of the nucleon to explain the NuTeV anomaly. It is shown that asymmetric strange quark-antistrage quark distributions may be a reasonable explanation for the NuTeV defect. On the other side, the NuTeV anomaly could be the evidence for the existence of asymmetric strange-antistrange quark distributions.     

关于奇异夸克物质的性质

基于以前的工作,导出了新的奇异夸克质量公式,并用于研究奇异夸克物质的性质,得到与MIT袋模型类似的结果.而且发现,新公式导致与以前有所不同的结果,即声速随能量密度的增加而趋向于极端相对论情况的速度减慢.     

模型参数对奇异星性质的影响

用有效质量口袋模型描述奇异夸克物质,研究了耦合常数和口袋常数的选取对奇异夸克物质的状态方程及奇异星性质的影响.结果表明,随着耦合常数和口袋常数的增大,奇异夸克物质的状态方程变软,相应的奇异星的引力质量和对应的半径均变小.当耦合常数从0.5增大到2.0时,奇异星的质量从1.43M_⊙(M_⊙=1.99×10³⁰ kg)减小到1.25M_⊙,相应的半径由8.3 km减小到7.7 km;当口袋常数B^1/4由160 MeV增大到175 MeV时,奇异星的质量和半径分别由1.47M_⊙和8.6 km减小到1.22M_⊙和7.4 km.这说明奇异夸克物质及奇异星的性质明显依赖于模型参数的取值. 关键词： 模型参数 奇异星 状态方程 质量-半径关系     

Bulk viscosity of strange quark matter in density dependent quark mass model

We have studied the bulk viscosity of strange quark matter in the density dependent quark mass model (DDQM) and compared results with calculations done earlier in the MIT bag model where u, d masses were neglected and first order interactions were taken into account. We find that at low temperatures and high relative perturbations, the bulk viscosity is higher by 2 to 3 orders of magnitude while at low perturbations the enhancement is by 1–2 order of magnitude as compared to earlier results. Also the damping time is 2–3 orders of magnitude lower implying that the star reaches stability much earlier than in MIT bag model calculations.     

Effects of Density-Dependent Quark Mass on Phase Diagram of Color-Flavor-Locked Quark Matter

Considering the density dependence of quark mass, we investigate the phase transition between the (unpaired) strange quark matter and the color-flavor-locked matter, which are supposed to be two candidates for the ground state of strongly interacting matter. We find that if the current mass of strange quark ms is small, the strange quark matter remains stable unless the baryon density is very high. If ms is large, the phase transition from the strange quark matter to the color-flavor-locked matter in particular to its gapless phase is found to be different from the results predicted by previous works. A complicated phase diagram of three-flavor quark matter is presented, in which the color-flavor-locked phase region is suppressed for moderate densities.     

浅谈近场光学

简要地介绍了近场光学的历史及现状，讨论了近场光学显微镜的构造、工作原理、工作方式及实际应用，并支近场光学的一些理论问题作了简明扼要的介绍，指出理论和实验上需要进一步发展的地方以及可能的途径。     

Radial oscillations of magnetized proto strange stars in temperature- and density-dependent quark mass model

We report on the study of the mass-radius (M–R) relation and the radial oscillations of magnetized proto strange stars. For the quark matter we have employed the very recent modification, the temperature- and density-dependent quark mass model of the well-known density-dependent quark mass model. We find that the effect of magnetic field, both on the maximum mass and radial frequencies, is rather small. Also a proto strange star, whether magnetized or otherwise, is more likely to evolve into a strange star rather than transform into a black hole.     

Equation of state in hybrid stars and the stability window of quark matter

Properties of hybrid stars with a mixed phase composed of asymmetric nuclear matter and strange quark matter are studied. The quark phase is investigated by the quark quasiparticle model with a self-consistent thermodynamic and statistical treatment. We present the stability windows of the strange quark matter with respect to the interaction coupling constant versus the bag constant. We find that the appearance of the quark–hadron mixed phases is associated with the meta-stable or unstable regions of the pure quark matter parameters. The mass–radius relation of the hybrid star is dominated by the equation of state of quark matter rather than nuclear matter. The contour plots of the maximum mass of the hybrid star are shown in the plane of the coupling constant and the bag constant.     

Strange Quark Matter and Strangelets in a Strong Magnetic Field

We study the stability properties of magnetized strange quark matter and strangelets under a strong magnetic field in the MIT bag model. The free energy per baryon of strange quark matter feels a great influence from the magnetic field. At the field strength about 10¹⁷G, the magnetized strange quark matter becomes more stable. Considering the finite size effect, the magnetic influence on strangelets becomes complicated. For a given magnetic field, there exists a critical baryon number, below which the magnetized strangelets have lower energy than the non-magnetized strangelets. For the field strength of 5× 10¹⁷G, the critical baryon number is A_c ～ 100. Generally, the critical baryon number increases with the decreasing external magnetic field. When the field strength is smaller than 10¹⁷G, the critical baryon number goes up to A_c～ 10⁵. The stable radius, electric charge, and quark flavor fractions of magnetized strangelets are shown.     

新的质量标度下奇异夸克物质的电荷与临界密度

应用自恰的热力学方式确定夸克质量公式中的参数,并进一步证明,在新的质量标度下,适量的负电荷仍然可以降低奇异夸克物质的临界密度,从而有利于在重离子碰撞实验中寻找strangelets.当然,过量的负电荷仍将使味平衡成为不可能.