Quantum Field Theory and Cosmology

该项目涉及与N. Tsamis（克里特岛大学），T. Prokopec（海德堡大学）以及PI的研究生在宇宙学量子场论效应的一般领域的许多合作研究。其中包括：(1)将标准宇宙摄动近似与PI和Tsamis最近获得的精确解进行比较；(2)一种计算量子引力对暴胀影响的方法；(3)建立一个模型，其中观测到的物质超过反物质是在暴胀期间产生的。(4)计算由带电无质量标量粒子在膨胀结束后引起的真空极化的变化；(5)研究是否可以建立一种非常不稳定的替代引力理论，在不需要暗物质的情况下解释宇宙物体的运动。(6)用自然几何物体表示膨胀过程中带电无质量标量粒子的真空极化；(7)在局域德西特宇宙学背景下，发展了计算量子引力效应的改进形式。问题(1)与WMAP卫星对宇宙微波各向异性的精确测量和未来计划的各种任务有关。标准近似技术几乎肯定足以从简单的暴胀模型中计算出原始光谱，但如果适用于外来模型，PI和Tsamis得到的精确结果可能非常有用。问题(2)的成功结果将彻底改变暴胀宇宙学的范式，解决它的两个主要问题(为什么初始状态是均匀的，足以开始暴胀？为什么观测到的宇宙常数如此之小？)并将其转化为预测理论。问题(3)的成功结果将解决长期存在的难题，即膨胀倾向于消除物质超过反物质的过剩。问题(4)应该解决的问题是，暴胀是否提供了小而宇宙尺度的磁场，作为我们在当今星系和星系团中观测到的磁场的种子。问题(5)代表了用另一种引力理论而不是暗物质理论来解释宇宙运动的最后现实希望。问题（6-7）代表了形式主义的渐进式进步，对研究生初学者来说是很好的练习。

The project involves a number of areas of collaborative research with N. Tsamis (U. of Crete), T. Prokopec (U. of Heidelberg), and the PI's graduate students in the general area of quantum field theoretic effects in cosmology . These include: (1) Comparing standard cosmological perturbation approximations with the exact solution recently obtained by the PI and Tsamis; (2) A method to calculate the effect of quantum gravity on inflation; (3) Developing a model in which the observed excess of matter over anti-matter is generated during inflation. (4) Computing what happens to the vacuum polarization induced by charged, massless scalar particles after the end of inflation; (5) Investigating whether a very slightly unstable, alternate theory of gravitation can be constructed which explains the motions of cosmological objects without the need for dark matter. (6) Expressing the vacuum polarization of charged massless scalar particles in terms of the natural geometrical objects during inflation; (7) Developing an improved formalism for computing quantum gravitational effects in a locally de Sitter-cosmology background. Problem (1) is relevant to the precision measurements of the cosmic microwave anisotropy by the WMAP satellite and the various missions planned for the future. Standard approximation techniques are almost certainly sufficient to compute the primordial spectrum from simple models of inflation but the exact result obtained by the PI and Tsamis may be very useful if an exotic model pertains. A successful outcome for problem (2) would completely change the paradigm of inflationary cosmology, resolving two of its major problems (why was the initial state homogeneous enough to begin inflating? and why is the observed cosmological constant so small?) and transforming it into a predictive theory. A successful outcome for problem (3) would resolve the long-standing conundrum that inflation tends to wipe out the excess of matter over anti-matter. Problem (4) should settle the issue of whether or not inflation provided the small but cosmological scale magnetic fields that served as the seeds of the fields we observe in present-day galaxies and galactic clusters. Problem (5) represents the last realistic hope for explaining cosmological motions using an alternate theory of gravitation rather than dark matter. Problems (6-7)represent incremental advances in formalism and good exercises for beginning graduate students.