The Origin of Matter in the Universe

早期宇宙从暴胀结束到热化等离子体形成的短暂时期是宇宙学中最不为人所知的时期之一。在那个被称为“再加热”的时代，我们今天看到的粒子、场和有效的低能相互作用都得到了发展，但描述这段时间所需的高能物理尚不清楚，而再加热的建模需要大规模的数值计算。PI与人合作编写了LATTICEEASY，这是最广泛使用的模拟再加热时代的程序。然而，到目前为止，大多数模拟都局限于不切实际的相互作用标量场的简单模型。PI打算扩展他的代码的功能，使其能够在并行处理器集群上运行，并在其计算中包含规范字段。利用这些扩展功能，他将在复杂的高能物理模型中模拟再加热，并提取可测试的预测。了解预热是很重要的，因为它引入了额外的“处理”（引力波，拓扑缺陷），人们可能会用它来约束暴胀中涉及的物理。其他与暴胀物理学相关的观测数据，如CMB，为暴胀模型提供了约束，但就其本质而言，并不能告诉我们暴胀如何与其他场耦合。如果我们要超越暴胀的现象学模型，真正开始讨论将暴胀嵌入一个能够与粒子物理的其他领域建立联系的模型中，有关耦合的信息将是至关重要的。PI打算开发一个培养本科生数值计算能力的项目。这将包括让本科生研究助理编写和运行数值模拟，为史密斯物理专业的两门必修课程创建计算单元，并围绕PI宇宙学研究的例子开发一门计算课程。

The brief period in the early universe from the end of inflation until the development of a thermalized plasma is one of the least understood eras in cosmology. During that era, which is known as "reheating," the particles, fields, and effective low-energy interactions we see today all developed, but the high-energy physics required to describe that time is not known and modeling reheating requires large-scale numerical computations. The PI has coauthored LATTICEEASY, the most widely used program for simulating the reheating era. Most simulations to date, however, have been limited to unrealistically simple models of interacting scalar fields. The PI intends to extend the capabilities of his code to run on clusters of parallel processors and to include gauge fields in its calculations. Using those extended capabilities he will simulate reheating in complex models of high-energy physics and extract testable predictions. An understanding of preheating is important because it introduces extra "handles" (gravitational waves, topological defects) that one might use to constrain the physics involved in inflation. Other observables related to inflationary physics such as the CMB provide constraints on inflation models, but by their nature don't tell us anything about how the inflaton couples to other fields. Information about the couplings will be crucial if we are to move beyond phenomenological models of inflation and really start talking about embedding the inflaton in a model capable of making contact with other areas of particle physics. The PI intends to develop a program for training undergraduate students in numerical computation. This will include involving undergraduate research assistants in writing and running numerical simulations, creating computational units for two of the required courses in the Smith physics major and developing a course on computation built around examples drawn from the PI's cosmological research.