报告时间：2026年1月23日（星期五）9:00-10:30
报告地点：翡翠湖校区物理楼302室
报 告 人：Giovanna Cottin 助理教授
工作单位：智利天主教大学
举办单位：物理学院
报告简介：
No significant deviations from the Standard Model predictions have been observed at particle physics experiments, except for neutrino masses. On the other hand, astrophysical evidence for dark matter also points to new physics. In theories beyond the Standard Model of particle physics, the new particles in the so-called dark sector can have large lifetimes, commonly referred to as long-lived particles (LLPs). These hypothetical states could travel macroscopic distances before decaying inside particle detectors, thus yielding more exotic signatures at colliders as opposed to promptly decaying states.
In this talk, I will motivate the quest for new, long-lived physics at colliders able to explain dark matter. In the models to be discussed, dark matter can come from scalar triplets, doublets or a complex singlet. It can be produced via freeze-out or freeze-in. For freeze-out, I will focus on scotogenic-like models, where neutrino masses can additionally be explained. For the latter, the impact of the cosmic reheating dynamics on dark matter freeze-in production will be discussed. All in all, new dark sector physics may be escaping detection due to its long-lived nature. I will emphasize the crucial role of (re-)interpreting long-lived particle signatures at the LHC and the proposed Future Circular Collider (FCC), and how this may help uncover the nature of the dark sector.
在粒子物理实验中，除了中微子质量之外，尚未观测到显著偏离标准模型预言的现象。另一方面，天体物理学中关于暗物质的证据同样指向新的物理。在粒子物理超越标准模型理论中，所谓暗扇区的新粒子可能具有较长的寿命，通常被称为长寿命粒子（LLPs）。这些假想粒子态可能在粒子探测器中飞行一段宏观距离后才衰变，因此，与迅速衰变的粒子态相比，在对撞机上会产生更加奇特的信号。在本报告中，我将讨论在对撞机上寻找新的、能够解释暗物质的长寿命粒子物理及其相关动机。在我将讨论的模型中，暗物质可能来自标量三重态、双重态或复单态。它可以通过冻出或冻入机制产生。对于 冻出而言，我将聚焦于类 scotogenic 的模型，在其中还可以同时解释中微子质量。对于冻入，则会讨论宇宙再加热动力学对暗物质冻入产生机制的影响。总而言之，新的暗扇区物理可能因为其长寿命而一直逃脱探测。我将强调在 LHC 以及未来环形对撞机（FCC）上对长寿命粒子信号进行（再）解释所起到的关键作用，以及其如何帮助我们揭示暗扇区的本质。
报告人简介：
Giovanna Cottin is an assistant professor at the Pontificia Universidad Católica de Chile. She received her Ph.D. from the University of Oxford in 2017 and subsequently held postdoctoral positions at Taiwan University (Taiwan, China) and the Pontificia Universidad Católica de Chile (Chile) between 2017 and 2020. From 2020 to 2023, she served as an assistant professor and later an associate professor at Universidad Adolfo Ibáñez. Since 2023, she has been an associate researcher at SAPHIR in Chile while holding a position as an assistant professor at the Pontificia Universidad Católica de Chile.
