Quantum Field Theory and Cosmology

该项目涉及与克里特大学的N.Tsamis、海德堡大学的T.Prokopec以及PI的研究生在宇宙学中量子场论效应的一般领域进行合作研究的一些领域。其中包括：(1)比较标准的宇宙学微扰近似与PI和Tsamis最近获得的精确解；(2)计算量子引力对膨胀的影响的方法；(3)建立一个模型，在该模型中，观测到的物质超过反物质的过剩是在膨胀过程中产生的。(4)计算膨胀结束后由带电的无质量标量粒子引起的真空极化会发生什么；(5)研究是否可以建立一个非常不稳定的替代引力理论来解释宇宙物体的运动，而不需要暗物质。(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)发展了一种计算局域de Sitter宇宙学背景下量子引力效应的改进形式。问题(1)涉及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飞行任务。标准的近似技术几乎肯定足以从简单的暴涨模型计算原始频谱，但如果一个奇异的模型适用，PI和Tsamis得到的确切结果可能非常有用。问题(2)的成功结果将彻底改变膨胀宇宙学的范式，解决它的两个主要问题(为什么初始状态足够均匀，可以开始膨胀？为什么观测到的宇宙学常数这么小？)并将其转化为预测性理论。问题(3)的成功结果将解决一个长期存在的难题，即通货膨胀往往会抹去多余的物质，而不是反物质。问题(4)应该解决的问题是，膨胀是否提供了小但宇宙尺度的磁场，这些磁场是我们在今天的星系和星系团中观察到的磁场的种子。问题(5)代表了使用另一种引力理论而不是暗物质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，也是研究生入门的好练习。

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.