满足“欧几里德条件”的坍缩球

A density theorem for asymptotically hyperbolic initial data satisfying the dominant energy condition

When working with asymptotically hyperbolic initial data sets for general relativity it is convenient to assume certain simplifying properties. We prove that the subset of initial data sets with such properties is dense in the set of physically reasonable asymptotically hyperbolic initial data sets. More specifically, we show that an asymptotically hyperbolic initial data set with non-negative local energy density can be approximated by an initial data set with strictly positive local energy density and a simple structure at infinity, while changing the mass arbitrarily little. This is achieve…

增强欧几里德超对称性、11维超引力和$SU(\infty)$ Toda方程

Enhanced Euclidean supersymmetry, 11D supergravity and $SU(\infty)$ Toda equation

我们展示了如何将具有非零宇宙学常数的Einstein-麦克斯韦方程组的解提升到具有非零通量的11维超引力理论的解。这就产生了一类11维度量，它是由$SU(\infty)$ Toda方程的解给出的。我们给出了一个正则解的例子，并分析了它的超对称性。我们还分析了N=2最小规范超引力的Killing旋量方程在四维欧几里德空间中的可积条件。我们得到了额外的Killing旋量存在的必要条件，对应于超对称性的增强。若Weyl张量是反自对偶的，则满足这些条件的超对称度量由$SU(\infty)$ Toda方程的可分解给出.否则，它们是ambi-Kähler的，并且共形等价于Calabi型的Kähler度量或两个黎曼曲面上的乘积度量。

f(R) wormholes embedded in a pseudo--Euclidean space $E^{5}$

This work is devoted to the study of analytic wormhole solutions within the framework of $f(R)$ gravity theory. To check the possibility of having wormhole structures satisfying energy conditions, by means of the class I approach the pair $\{Φ(r), b(r)\}$ describing the wormhole geometry has been obtained. Then, in conjunction with a remarkably $f(R)$ gravity model, the satisfaction of the null and weak energy conditions at the wormhole throat and its neighborhood is investigated. To do so, some constant parameters have been bounded restricting the space parameter. In this concern, the $f(R)$ …

Causal thermodynamics of a gravitational collapse model for an anisotropic fluid with dissipative flows

This paper presents a hydrodynamic and thermodynamic treatment of a radiant star model that undergoes a dissipative gravitational collapse, from a certain initial configuration until it becomes a black hole. The collapsing star consists of a locally anisotropic non-perfect fluid, where we explore the consequences of including viscous pressures, both shear and bulk viscosities, as well as radial heat flow. We analyze the temporal evolution of the heat flux, mass function, luminosity perceived by an observer at infinity and the effective surface temperature. It is shown that this simple exact mo…

二维简并时空因果结构的经典和量子意义

Classical and Quantum Implications of the Causality Structure of Two-Dimensional Spacetimes with Degenerate Metrics

利用无质量波动方程的整体解分析了具有退化度量的二维流形的因果结构。一些新的特征出现了。尽管没有一个传统的洛伦兹柯西曲面流形与欧几里德域是可能的唯一确定一个整体解决方案（如果它存在），满足良好定义的匹配条件，在退化曲线，从柯西数据某些类空曲线在洛伦兹区域。然而，一般来说，没有满足这样的匹配条件的全局解将与该数据一致。提请注意出现的一些障碍，禁止建设一个有界的运营商连接渐近单粒子状态。讨论了这些结果对酉量子场论存在性的影响。

广义Spinfoams

Generalized Spinfoams

我们重新考虑spinfoam动力学，最近推出的，在广义Kaminski-Kisielowski-Lewandowski（KKL）的版本，泡沫是不是双重的三角。我们研究欧几里德以及洛伦兹的情况。我们发现，这个理论仍然可以得到一个约束BF理论满足简单性约束，现在离散化的一般面向2-细胞复杂。这个限制意味着边界状态允许多面体的（量子）几何解释，推广了单纯情况下的四面体几何。我们还指出，这个约束的一般解决方案（施加弱）依赖于一个量子数r_f除了那些圈量子引力。当r_f=0时，我们计算顶点振幅，恢复出欧氏理论中的KKL振幅.我们评论的最终物理相关的r_f，和正式的方式来消除它。