Consortium for Fundamental Physics - Particle Cosmology and Fundamental Physics: From the Early to the Present Universe

粒子宇宙学是关于理解宇宙的。它解决了许多问题，比如：宇宙是如何开始的？它的组成成分是什么？是宇宙大爆炸还是宇宙一直存在？什么是暗物质，什么是暗能量，导致宇宙加速膨胀？多年来，宇宙学家和粒子物理学家已经建立了一个标准模型，很好地描述了观测到的宇宙特性。该模型称为LambdaCDM模型。它依赖于某种形式的暗物质，这种暗物质只能通过引力与普通物质相互作用。加速膨胀可以用恒定的暗能量密度（宇宙常数Lambda）来解释。根据这个模型，我们宇宙的历史始于一个奇点，随后是一个加速膨胀的时代，称为暴胀。更好地理解暴胀仍然是粒子宇宙学的目标之一。虽然LambdaCDM模型提出了许多问题，但它为解释观测到的宇宙特性提供了一个很好的起点。然而，最近我们的认识出现了一些裂缝。例如，测量宇宙当前膨胀率的不同方法存在很大差异。此外，暗物质的聚集也没有被完全理解。这些缺陷表明，LambdaCDM模型所依赖的一些假设可能需要改进。我们联盟的成员将通过开发将暴胀与暗能量物理联系起来的模型来研究早期宇宙的模型。他们将通过研究相互作用的粒子及其对结构形成的影响，进一步研究更精细的暗物质模型。我们的科学家正在研究加速膨胀的粒子物理学解释以及暗物质和暗能量之间可能的相互作用。在接下来的十年里，会有大量新的宇宙学和天体物理学数据出现，这些数据使科学家能够以越来越高的精度探测暗物质和暗能量的特性。我们将为暗物质发展新的理论，这些理论与目前的数据完全一致，但随着新数据的到来，我们可以进一步探索。大爆炸奇点是LambdaCDM模型的预测之一，它标志着物理定律的崩溃。物理学家认为，一个更完整的理论，将非常小的物理学（量子力学）与引力结合起来，将告诉我们当前的宇宙是如何形成的。我们的研究人员开发了早期宇宙的模型，并找到了用未来的观测来验证这些模型的方法。粒子物理学的理论不仅可以用宇宙学的考虑来检验。广义相对论，即爱因斯坦的引力理论，预言了黑洞的存在，黑洞是任何东西都无法逃脱的空间区域，甚至连光也无法逃脱。我们的科学家正在研究黑洞稳定的条件，以及它们如何影响周围粒子的相互作用，包括假设的极轻粒子轴子，它可能是宇宙中的暗物质。

Particle cosmology is about understanding the Universe. It addresses many questions such as: How did the Universe begin? What are its constituents within it? Was there a Big Bang or was the Universe always there? What is dark matter and what is dark energy, that causes the expansion of the Universe to accelerate? Over the years, cosmologists and particle physicists have developed a standard model which describes the observed properties of the Universe very well. The model is called the LambdaCDM model. It relies on some form of dark matter which interacts with ordinary matter only via gravity. The accelerated expansion is explained by a constant dark energy density (the cosmological constant Lambda). According to this model, the history of our Universe began with a singularity and a subsequent era of accelerating expansion, called inflation. It remains one of the goals of particle cosmology to understand inflation better. While the LambdaCDM model raises many questions, it provides a good starting point to explain the observed properties of the Universe. Recently, however, some cracks have appeared in our understanding. For example, different methods to measure the current expansion rate of the Universe disagree by a wide margin. Additionally, the clustering of dark matter is also not fully understood. These cracks show that some of the assumptions on which the LambdaCDM model rests may be in need of refinement. Members of our Consortium will study models of the very early Universe, by developing models which relate inflation to the physics of dark energy. They will further study more refined models of dark matter, by studying interacting particles and their impact on the formation of structures. Our scientists are working on particle physics explanations of the accelerated expansion and the possible interplay between dark matter and dark energy. There is a plethora of new cosmological and astrophysical data coming in during the next decade which allow scientists to probe the properties of dark matter and dark energy with ever-growing accuracy. We will develop new theories for the dark sector, which are in full agreement with current data but can be probed further with new data coming in. The Big Bang singularity, one of the predictions of the LambdaCDM model, signals a breakdown of the laws of physics. Physicists believe that a more complete theory, which combines the physics of the very small (quantum mechanics) with gravity, will tell us how the current universe came into existence. Our researchers develop models of the very early universe and find ways to test these with future observations. Theories of particle physics can not not only be tested by cosmological considerations. General Relativity, Einstein's theory of Gravity, predicts the existence of black holes, regions of space from which nothing can escape, not even light. Our scientists are studying the conditions under which BHs are stable and how they affect the interactions of particles around them, including hypothetical extremely light particles called axions, which could be the dark matter in the universe.