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Quantum Field Theory and Cosmology

量子场论和宇宙学

基本信息

批准号：
2207514
负责人：
Richard Woodard
金额：
$ 18万
依托单位：
University of Florida
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
2022
资助国家：
美国
起止时间：
2022-09-01 至 2025-08-31
项目状态：
未结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=2207514&HistoricalAwards=false
关键词：
Quantum Field Theory Cosmology

项目摘要

During the earliest moments of its existence the Universe underwent such rapid, and accelerated, expansion that quantum fluctuations were ripped out of empty space to produce a vast, and ever-growing ensemble of gravitational radiation. This radiation provided a sort of medium which affected long range forces and also how things propagate, the same way that water changes electric forces and the propagation of light. Because ever-more radiation was produced, its effects grew with time, and sometimes also with space. It is possible that remnants of these effects became strong enough to survive to the current day, and that they provide explanations for some of the puzzles which arise when one tries to understand the large scale Universe in terms of ordinary matter with Einstein’s theory of gravitation. The goal of this project is to develop reliable techniques for calculating these effects when they become strong, and modeling the results as changes in Einstein’s theory of gravitation. The project involves extensive international collaborations with physicists in the Czech Republic, France, Greece, Netherlands and Taiwan. The project provides summer support for two graduate students per year, whose education enhances the pool of STEM talent available to the United States. It should also be noted that, although the PI selects students on the basis of merit, over half of his past graduate students have been female or Hispanic. During the fall of 2021 the PI and collaborators showed that the large logarithms induced by nonlinear sigma models (whose derivative interactions mimic those of gravity) on de Sitter background can be summed up by combining variants of Starobinsky's stochastic formalism and the renormalization group. They also demonstrated that that the exchange potential of a massless, minimally coupled scalar (MMCS) provides the simplest venue for purging gauge dependence by including quantum gravitational correlations from the source and observer. The recent breakthrough on resummation, coupled with steady progress on approximating effective potentials in realistic geometries, has also provided important insights for expressing graviton loop corrections in terms of simple, nonlocal modifications of gravity. Finally, the effective potential results suggest a dramatic simplification for computations of reheating from longitudinal vectors. To exploit this recent progress the PI and his graduate students will continue their collaborations with Dr. Drazen Glavan (CEICO, Czech Republic), Prof. Cedric Deffayet (IAP, France), Prof. Shun-Pei Miao (NCKU, Taiwan), Prof. Tomislav Prokopec (U. Utrecht, Netherlands) and Prof. Nikolaos Tsamis (U. Crete, Greece) on four main projects: Generalize the new resummation technique to quantum gravity; demonstrate that source and observer correlations eliminate gauge dependence in the MMCS exchange potential on de Sitter background; develop and explore nonlocal modifications of gravity; and show how reheating can be analyzed using cosmological Coleman-Weinberg potentials.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

在宇宙存在的最早时刻，宇宙经历了如此快速和加速的膨胀，以至于量子涨落被从空荡荡的空间中撕裂出来，产生了一个巨大的、不断增长的引力辐射系综。这种辐射提供了一种影响远距离力的介质，也影响了物体的传播，就像水改变电力和光的传播一样。由于产生的辐射越来越多，其影响随着时间的推移而增加，有时也随着空间的增加而增加。有可能这些效应的残余变得足够强大，直到今天仍然存在，并且它们为人们试图用爱因斯坦的引力理论来理解大尺度宇宙中的普通物质时出现的一些难题提供了解释。该项目的目标是开发可靠的技术来计算这些效应，当它们变得强大时，并将结果建模为爱因斯坦引力理论的变化。该项目涉及与捷克共和国，法国，希腊，荷兰和台湾的物理学家进行广泛的国际合作。该项目每年为两名研究生提供暑期支持，他们的教育增强了美国的STEM人才库。还应该指出的是，虽然PI根据成绩选择学生，但他过去的研究生中有一半以上是女性或西班牙裔。在2021年秋季，PI和合作者表明，在de Sitter背景下由非线性sigma模型（其导数相互作用模拟引力）引起的大规模的非线性可以通过结合Starobinsky的随机形式主义和重整化群的变体来总结。他们还证明，无质量最小耦合标量（MMCS）的交换势通过包含来自源和观测者的量子引力相关，为清除规范依赖性提供了最简单的场所。最近的突破，再加上稳定的进展，近似有效的潜力在现实的几何形状，也提供了重要的见解表示引力子环的修正，在简单的，非局部的修改重力。最后，有效势的结果表明，一个戏剧性的简化计算的再热从纵向矢量。为了利用这一最新进展，PI和他的研究生将继续与Drazen Glavan博士（CEICO，捷克共和国），Cedric Deffayet教授（IAP，法国），Shun-Pei Miao教授（NCKU，台湾），Tomislav Proklovan教授（U.乌得勒支，荷兰）和教授尼古拉斯Tsamis（美国）。希腊克里特岛）的四个主要项目：将新的重定技术推广到量子引力;证明源和观测者的相关性消除了德西特背景下MMCS交换势中的规范依赖性;发展和探索引力的非局域修正;并展示如何使用宇宙学的科尔曼来分析再加热-温伯格潜力。该奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。