Cosmological phase transitions: field theoretical and numerical improvements

宇宙相变：场理论和数值改进

• 批准号: 387095756
• 负责人: Professor Dr. Haye Hinrichsen
• 金额: --
• 依托单位: Lehrstuhl für Theoretische Physik II: Theoretische Elementarteilchenphysik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/387095756?language=en
• 关键词: Cosmological; phase; transitions; field; theoretical

One of the biggest riddles in cosmology is the one of the observed baryon-asymmetry in the Universe: why does one observe much more baryons than anti-baryons. In principle it should be possible to explain this from the point of view of elementary particle physics via the electroweak phase transition which took place in the early Universe. However, the Standard Model fails in this respect despite the fact that it contains all required structural ingredients. Thus, it needs to be extended.In this project we will first develop fieldtheoretical and numerical methods, which allow for an improved calculation of this phase transition. It can roughly be divided into three steps: (i) the nucleation phase, in which bubbles with the energetically favourable phase nucleate, (ii) the expansion of these bubbles and (iii) collisions and coalescence of the bubbles. We will calculate the so-called bounce-solution within the 2PI-formalism, which is used to describe out-of-equilibrium phenomena. In this way we obtain a model-specific starting profile for the bubble wall and we do not rely on the usual arctan-ansatz. Moreover, one can check if one is indeed close to thermal equilibrium as it is usually assumed in the literature. This is in particular relevant for extensions of the Standard Model. In the second step we will apply these techniques to some of these extensions. We will study in particular models with an extended Higgs sector, neutral naturalness models as well as composite Higgs models taking into account the latest available LHC-data.

宇宙学中最大的谜团之一是宇宙中观察到的重子不对称性：为什么人们观察到的重子比反重子多得多。原则上，从基本粒子物理学的角度，通过发生在早期宇宙中的电弱相变来解释这一点应该是可能的。然而，标准模型在这方面失败了，尽管它包含了所有必要的结构成分。因此，它需要被扩展。在这个项目中，我们将首先开发fieldtheoretical和数值方法，这允许一个改进的计算这种相变。它可以大致分为三个步骤：（i）成核阶段，其中具有能量有利相的气泡成核，（ii）这些气泡的膨胀和（iii）气泡的碰撞和合并。我们将在2 PI形式主义中计算所谓的反弹解，它用于描述平衡现象。以这种方式，我们得到一个模型特定的气泡壁的起始配置文件，我们不依赖于通常的arctan-anomaly。此外，可以检查是否确实接近文献中通常假设的热平衡。这对于标准模型的扩展尤其重要。在第二步中，我们将把这些技术应用于其中的一些扩展。我们将特别研究扩展希格斯扇区模型，中性自然模型以及考虑到最新可用LHC数据的复合希格斯模型。