Probing Dark Sector Physics in Collider and Cosmology

这个奖项资助了美国圣母大学蔡育信教授的研究活动。想象一下，有可能存在另一个“隐藏”世界，与我们共存于同一时空，但我们实际上看不到它，因为隐藏世界与我们之间的相互作用非常微弱。 虽然这听起来像科幻小说，但粒子物理学和宇宙学的最新发展表明，宇宙中可能存在一个不可见的部分。 事实上，这样一个隐藏扇区的存在将有助于解释几个长期存在的理论和观测难题。 蔡教授的研究旨在利用引力波、早期宇宙学和高能粒子对撞机（如大型强子对撞机）来揭示这些隐藏的世界。 因此，这项研究通过促进科学在发现新的物理定律和自然世界新成分方面的进步来促进国家利益。 这项工作还将产生若干更广泛的影响。 这项工作的结果不仅将指导未来的实验和技术开发，还将涉及研究生和博士后，从而为开始这一领域研究的初级物理学家提供关键培训。 蔡教授亦计划就其研究成果作公开讲座，并协助发展高中生外展计划。蔡教授将研究随机引力波背景下的能量扰动。 他还将研究早期宇宙中隐藏粒子产生的引力波信号的非高斯特征的大小。 这种分析的结果将有助于识别引力波探测器，这些探测器可以观察到来自隐藏世界的能量波动，这些能量波动仅通过引力与我们相互作用。 蔡教授亦会研究解决希格斯层次问题的模型的宇宙学特征，例如镜像双希格斯模型和N-自然模型。 基于这些场景可以在隐藏的粒子之间产生声学振荡的想法，我们可以通过它们在早期宇宙中引起的重力扰动的变化来研究这些模型。 利用LHCb实验目前和未来的敏感性，蔡教授还将开发新的方法来研究长寿命粒子的特征，这些粒子不仅与常规物质耦合，还与隐藏世界中的粒子耦合。这个奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This award funds the research activities of Professor Yuhsin Tsai at the University of Notre Dame.Imagine the possibility that there is another "hidden" world that coexists with ours in the same space and time, but which is practically invisible to us because the interactions between the hidden world and ours are very weak. While this may sound like science fiction, recent developments in particle physics and cosmology have shown that an invisible sector of the universe might actually exist. Indeed, the existence of such a hidden sector would help explain several long-standing theoretical and observational puzzles. Professor Tsai’s research is aimed at using gravitational waves, early-time cosmology, and high-energy particle colliders (such as the Large Hadron Collider) to uncover such hidden worlds. As such, this research advances the national interest by promoting the progress of science in the discovery of new physical laws and new components of the natural world. This work will also have several broader impacts. The results of this work will not only guide future experiments and technology development, but also involve graduate students and postdocs, thereby providing critical training for junior physicists beginning research in this field. Professor Tsai also intends to give public lectures on his research results and help to develop outreach programs for high-school students.More technically, Professor Tsai will study energy perturbations in the stochastic gravitational-wave background. He will also study the size of non-Gaussian signatures of the gravitational-wave signal produced by the hidden particles in the early universe. The result of this analysis will help in the identification of the gravitational-wave detectors that can observe the energy fluctuations from the hidden world that interacts with us solely through gravity. Professor Tsai will also study the cosmological signatures of models that address the Higgs hierarchy problem, such as the Mirror Twin Higgs model and the N-Naturalness model. Based on the idea that these scenarios can produce acoustic oscillations between hidden particles, we can study these model through the changes they induce for gravity perturbations in the early universe. Exploiting the current and the expected future sensitivity of the LHCb experiment, Prof. Tsai will also develop new ways to study the signature of long-lived particles that couple not only to regular matter but also to particles in the hidden world.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.