Identifying Elusive Particles and Interactions with Cosmology and Colliders

This award funds the research activities of Professors Antonio Delgado, Adam Martin, and Yuhsin Tsai at the University of Notre Dame. Particle physics today has an abundance of data from colliders, dark matter detectors, and cosmological measurements. The primary goal of phenomenologists is to scour this wealth of information for signs of new physics, especially particles that are either too heavy to produce in large quantities at colliders or that interact only weakly with the Standard Model. Under this grant, the Notre Dame group will explore new physics through various approaches. They will use cosmological data from the cosmic microwave background (CMB) and the large-scale structure (LSS) of the Universe and study Effective Field Theory, which connects experimental data to new physics phenomena in a way consistent with the symmetries and rules of nature. Through these efforts, the proposed research advances national interests by promoting scientific progress towards understanding the fundamental laws of nature. Furthermore, this research will have a broad impact by guiding future experimental searches and involving close collaboration with experimenters at Notre Dame, Fermilab, and CERN. In addition to this research, Delgado, Martin, and Tsai will continue their teaching (at both graduate and undergraduate levels), outreach efforts through the QuarkNet program, and the organization of domestic and international conferences. More technically, Prof. Tsai will use cosmological data to study strong phase transitions occurring in the late-time universe and measure the lifetime of Standard Model neutrinos. Prof. Martin and Prof. Tsai will also investigate cosmological heavy particle production, focusing on localized signals in the CMB and LSS. Prof. Martin will work on improving Standard Model effective field theory-based searches for new phenomena, emphasizing uncertainties from higher-order terms. Additionally, Prof. Martin and Prof. Delgado will study supersymmetric Effective Field Theories using on-shell amplitude methods. 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.