EAPSI: Toward Cosmic Expansion in the Framework of Supergravity Theory

由于引力相互作用的吸引性质，人们会认为我们的宇宙正在以递减的速度膨胀。然而，观测表明，我们的宇宙目前正在经历加速膨胀，有许多证据表明，在原始宇宙中发生了更快的膨胀。尽管已经提出了许多现象学模型，但这些机制背后的物理起源尚不清楚。特别是，是什么样的粒子导致了膨胀？有没有可能在一个统一的理论框架下将这些粒子与迄今已发现的所有其他粒子相适应？获奖者将与超对称性、超重力和粒子物理宇宙学的领先专家村山仁教授以及日本东京卡夫利宇宙物理和数学研究所的其他潜在合作者一起，试图在超对称性的理论框架下扩展我们对这些基本问题的理解，超对称性是一个潜在的候选者，可以统一粒子物理学中所有已知的相互作用。我们的宇宙在当前时代的加速膨胀通常被归因于一种奇异的粒子/场的形式，称为暗能量。从现象学的观点来看，一个具有足够平坦的势的标量场，被称为QuintEssence，可以描述暗能量。在这个项目中，我们的目标是在超引力的框架下，构建一个与超对称粒子物理标准模型相耦合的经典暗能量模型。当粒子物理的经典模型与超对称模型相结合时，经典模型的平面势一般会被超对称破缺所破坏。因此，我们考虑一种形式的卡勒势，它受到膜世界情景的启发，隔离了粒子物理和精髓部门。然后，我们将尝试在此基础上建立一个模型，并调查各种观测约束。该奖项由东亚和太平洋暑期学院项目资助一名美国研究生的暑期研究，由NSF和日本科学促进会共同资助。

Due to the attractive nature of gravitational interaction, one would expect that our universe is expanding at a decreasing rate. Nevertheless, observations have shown that our universe is undergoing accelerating expansion at present era, and there is much evidence to indicate that a much more rapid expansion occurred in the primordial universe. Even though many phenomenological models have been proposed, the physical origin behind these mechanism is yet unknown. In particular, what kind of particles is responsible for the expansion? Is it possible to accommodate these particles with all other particles that have been discovered so far under a unified theoretical framework? With Prof. Hitoshi Murayama, a leading expert on supersymmetry, supergravity and particle physics cosmology, and with other potential collaborators at Kavli Institute for the Physics and Mathematics of the Universe at Tokyo, Japan, the awardee will attempt to extend our understanding of these fundamental questions under the theoretical framework of supersymmetry, which is a potential candidate that can unify all known interactions in particle physics.The accelerating expansion of our universe at current the era is often attributed to an exotic form of particle/field called dark energy. From the phenomenology point of view, a scalar field with a sufficiently flat potential, named quintessence, could describe dark energy. In this project we aim to construct a quintessence dark energy model that couples to the supersymmetric Standard Model of particle physics, in the framework of supergravity. When combining quintessence model with supersymmetric model of particle physics, generically the flat potential of the quintessence will be spoiled by the supersymmetry breaking. We therefore consider a form of Kahler potential that sequesters the particle physics and quintessence sector, inspired by the brane-world scenario. We will then attempt to build a model based on this and investigate various observational constraints. This award under the East Asia and Pacific Summer Institutes program supports summer research by a U.S. graduate student and is jointly funded by NSF and the Japan Society for the Promotion of Science.