String theory, hight emperature QCD and inflationary cosmology

弦理论、高温 QCD 和暴涨宇宙学

• 批准号: 326716-2009
• 负责人: Dasgupta, Keshab
• 金额: $ 4.74万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Subatomic Physics Envelope - Individual
• 财政年份: 2010
• 资助国家: 加拿大
• 起止时间: 2010-01-01 至 2011-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=457625
• 关键词: String; theory; hight; emperature; QCD

In my last grant proposal I summarised my works on two basic areas of research: string cosmology and flux compactifications. I have continued on these two topics, and have also started working on thermal field theories like high temperature QCD etc using tools of string theory. The field of high temperature QCD has recently become very active due to some interesting inputs from string theory. String theory predicts that certain gauge theories could be studied from dual gravity backgrounds where all calculations of these gauge theories have one-to-one correspondences in the gravity theories. This would mean, in particular, that certain non-trivial calculations of gauge theories (that were thought to be rather impossible to do using conventional techniques) could now be easily performed using this new duality. Using these techniques, a year ago it was found that the ratio of the viscosity of any thermal fluid to its entropy cannot be smaller than a certain number. This was a very surprising conclusion that came out directly from applying string theory methods (its difficult to predict this using conventional gauge theory techniques). Question however is whether this "bound" is robust. We have recently found that the predicted bound could be lowered by incorporating string theory corrections. However the analysis is highly involved and would require time and the efforts of few graduate students to work this out completely. It will be really fascinating if we could find a new bound here, as this would be the first concrete prediction of string theory for the real world.

在我的上一份资助提案中，我总结了我在两个基本研究领域的工作：弦宇宙学和通量紧致化。我继续研究这两个主题，并开始使用弦理论工具研究高温 QCD 等热场理论。由于弦理论的一些有趣的输入，高温 QCD 领域最近变得非常活跃。弦理论预测某些规范理论可以在双引力背景下进行研究，其中这些规范理论的所有计算在引力理论中都具有一一对应的关系。这尤其意味着，规范理论的某些重要计算（被认为使用传统技术不可能完成）现在可以使用这种新的对偶性轻松执行。使用这些技术，一年前发现任何热流体的粘度与其熵的比率不能小于某个数字。这是一个非常令人惊讶的结论，是直接从应用弦理论方法得出的（使用传统的规范理论技术很难预测这一点）。然而问题是这个“界限”是否稳健。 我们最近发现，通过结合弦理论修正可以降低预测界限。然而，分析的复杂度很高，需要时间和少数研究生的努力才能完全解决这个问题。如果我们能在这里找到一个新的界限，那将非常令人着迷，因为这将是弦理论对现实世界的第一个具体预测。