广义不确定关系与黑洞附近的热力学量

利用广义不确定关系修正的态密度计算了一般球对称静态黑洞附近无质量共形不变标量场、中微子场、电磁场、无质量Rarita-Schwinger场和引力场的热力学量.结果表明，黑洞附近的热力学量不仅依赖于黑洞的特征，还依赖于粒子的自旋和最小距离的尺度. 关键词： 广义不确定关系 一般球对称静态黑洞 热力学量     

随机横场与晶场作用混合自旋系统的热力学性质

利用有效场理论和切断近似，在伊辛模型的框架内考虑随机横场与晶场作用的混合自旋1/2 和自旋1系统的热力学性质。重点研究了晶场、横场和随机浓度对混合自旋系统相变的影响 ，研究发现在随机横场条件下，较小的晶场存在并不能改变临界横场阈值；取较大横场值时 在某些随机浓度的范围内出现重入相变现象，而取较小横场值时则没有出现重入相变现象。 给出了有关相图并进行了讨论。 关键词： 混合自旋系统 伊辛模型 热力学性质 随机横场     

Gibbons-Maeda黑洞附近中微子场的熵

从Gibbons-Maeda(G-M)时空背景下的线元出发,利用WKB近似,由自旋为1/2的中微子场方程求得径向波数pkr,在此基础上利用brick-wall方法计算了G-M黑洞附近中微子场的自由能和熵,并与标量场的熵作了比较,发现中微子场的主项熵是标量场的主项熵的7/8倍.     

梯形自旋链的一种规范场论的形式

考虑无质量费米场和规范场的Pauli相互作用项的系统,在这一理论中耦合常数为无量纲量.该模型等价于自旋1/2反铁磁XXZ量子链.如在模型中引入费米场的味自由度,则可定性描述二条自旋链的梯形结构系统.在这一系统中不再存在无能隙激发. 关键词： 梯形结构 规范场 自旋链     

Anti-de Sitter时空中黑洞量子熵的发散结构

用“brick- wall”模型研究了Anti-de Sitter时空中起源于电磁和引力场的黑洞量子熵的发散结构, 结果表明量子熵由线性发散项和对数发散项构成. 如果平衡温度选为Hawking温度，固有截断替代坐标截断，则线性发散项可化为正比于事件视界面积的形式；而对数发散项不仅依赖于黑洞的特征，也依赖于场的自旋，由于此项的存在，自旋场的贡献不再与标量场的贡献成正比. 关键词： 发散结构 黑洞熵 AdS时空 电磁和引力场     

具有长程相互作用S-1/2 XY链的研究

采用平均场Jordan-Wigner变换分析方法,研究了外场中且具有Z方向均匀长程相互作用自旋-1/2 XY链的热力学性质,得到了系统格点的亥姆赫兹自由能、内能、比热、磁化强度、磁化率等热力学量的解析表达式及其数值解,讨论了系统的一级和两级相变,数值结果在退化条件下与其他文献的结果符合很好.     

Anti-de Sitter时空内柱黑洞的量子熵

利用brick-wall方法计算了Anti-de Sitter时空内起源于Dirac场的柱黑洞的量子熵.结果表明，忽略远离围绕系统的真空的贡献时，量子熵包含了线性发散项和对数发散项，整个表达式的形式与标量场的不一样.无论整个对数项还是与自旋联系的子对数项都总是正的. 关键词： brick-wall方法 量子熵 柱黑洞 Dirac场     

匀强磁场与简谐势阱中荷电自旋-1/2费米子的热力学性质

基于准经典近似方法,研究了匀强磁场与简谐势阱中荷电自旋-1/2费米系统的热力学性质,给出了系统的粒子数、内能、比热、磁化强度和磁化率等热力学量的解析表达式.通过引入自旋因子描述电荷-磁场和自旋-磁场作用的相互竞争,并数值分析了自旋因子对系统磁化强度的影响.研究表明,系统呈现抗磁性还是顺磁性取决于自旋因子的值,二维荷电费米系统的磁性质与三维系统相似.     

具有长程相互作用S-1/2 XY链的研究

采用平均场Jordan - Wigner 变换分析方法,研究了外场中且具有Z方向均匀长程相互作用自旋－1/2 XY链的热力学性质,得到了系统格点的亥姆赫兹自由能、内能、比热、磁化强度、磁化率等热力学量的解析表达式及其数值解,讨论了系统的一级和两级相变,数值结果在退化条件下与其他文献的结果符合很好. 关键词： XY链')" href="#">XY链 平均场Jordan-Wigner变换 长程相互作用     

自旋团簇量子主方程的复合动力学对称性和热力学性质

基于三同核线型自旋团簇(每个粒子的自旋为S=1/2)的非自治量子主方程,研究了处于热辐射场中的自旋团簇的热力学性质.利用新颖的代数动力学方法,即引入动力学群的左右表象,不仅发现了自旋团簇的一个子空间态具有的SU(2)U(1)U(1)结构,而且对该子空间态在演化中所产生的耗散和退相干性质进行了计算.     

State equations for massless spin fields in static spherical spacetime filled with quintessence

The entropy density, energy density, pressure and equation of state for the gases of massless particles with spin s ≤ 2 around the static spherical black hole with quintessence are investigated by using the brick-wall method. It is shown that the state equations for spin fields in curved spacetime do not take the same forms as that in flat spacetime and contain additional terms with spin dependence. Then the character of the terms and the effect of quintessence and spin on them are discussed.     

Entropy of Spin Fields in Schwarzschild Spacetime

By using the Teukolsky master equation, we consider the gravitational,electromagnetic, and neutrino fields in Schwarzschild spacetime. The free energyand entropy of the spin fields are obtained in terms of the brick-wall model. Itis shown that the entropy of all the spin fields due to the presence of the eventhorizon is proportional to the surface area of the event horizon, and the entropyof the neutrino field is the absolute minimum.     

The physical meaning of the de Sitter invariants

We study the Lie algebras of the covariant representations transforming the matter fields under the de Sitter isometries. We point out that the Casimir operators of these representations can be written in closed forms and we deduce how their eigenvalues depend on the field’s rest energy and spin. For the scalar, vector and Dirac fields, which have well-defined field equations, we express these eigenvalues in terms of mass and spin obtaining thus the principal invariants of the theory of free fields on the de Sitter spacetime. We show that in the flat limit we recover the corresponding invariants of the Wigner irreducible representations of the Poincaré group.     

Gravity and Spin Forces in Gravitational Quantum Field Theory

In the new framework of gravitational quantum field theory(GQFT) with spin and scaling gauge invariance developed in Phys. Rev. D 93(2016) 024012-1, we make a perturbative expansion for the full action in a background field which accounts for the early inflationary universe. We decompose the bicovariant vector fields of gravifield and spin gauge field with Lorentz and spin symmetries SO(1,3) and SP(1,3) in biframe spacetime into SO(3) representations for deriving the propagators of the basic quantum fields and extract their interaction terms. The leading order Feynman rules are presented. A tree-level 2 to 2 scattering amplitude of the Dirac fermions, through a gravifield and a spin gauge field, is calculated and compared to the Born approximation of the potential. It is shown that the Newton's gravitational law in the early universe is modified due to the background field. The spin dependence of the gravitational potential is demonstrated.     

Gravity and Spin Forces in Gravitational Quantum Field Theory

In the new framework of gravitational quantum field theory (GQFT) with spin and scaling gauge invariance developed in Phys. Rev. D 93 (2016) 024012-1, we make a perturbative expansion for the full action in a background field which accounts for the early inflationary universe. We decompose the bicovariant vector fields of gravifield and spin gauge field with Lorentz and spin symmetries SO(1,3) and SP(1,3) in biframe spacetime into SO(3) representations for deriving the propagators of the basic quantum fields and extract their interaction terms. The leading order Feynman rules are presented. A tree-level 2 to 2 scattering amplitude of the Dirac fermions, through a gravifield and a spin gauge field, is calculated and compared to the Born approximation of the potential. It is shown that the Newton's gravitational law in the early universe is modified due to the background field. The spin dependence of the gravitational potential is demonstrated.     

A spin polarized disc

We present a solution to the gravitational field equations in a Riemann-Cartan spacetime. The solution describes a disc of infinite radius and finite thickness. The solution has three forms which depend on the size of the acceleration. The matter content of the disc is a rotating spin fluid with a constant z acceleration and a spin density polarized along the axis of rotation. The fluid has zero axial and tangential pressures. There is a radial pressure. The energy density and pressure are finite within the disc.     

Quantum Gravity,Information Theory and the CMB

We review connections between the metric of spacetime and the quantum fluctuations of fields. We start with the finding that the spacetime metric can be expressed entirely in terms of the 2-point correlator of the fluctuations of quantum fields. We then discuss the open question whether the knowledge of only the spectra of the quantum fluctuations of fields also suffices to determine the spacetime metric. This question is of interest because spectra are geometric invariants and their quantization would, therefore, have the benefit of not requiring the modding out of diffeomorphisms. Further, we discuss the fact that spacetime at the Planck scale need not necessarily be either discrete or continuous. Instead, results from information theory show that spacetime may be simultaneously discrete and continuous in the same way that information can. Finally, we review the recent finding that a covariant natural ultraviolet cutoff at the Planck scale implies a signature in the cosmic microwave background (CMB) that may become observable.