New Probes of Physics Beyond the Standard Model

This award funds the research activities of Professors Joshua Ruderman and Neal Weiner at New York University. The Standard Model of particle physics successfully describes an enormous range of observed phenomena, yet it leaves fundamental questions unanswered --- most strikingly the identity of the dark matter that makes up most of the mass in galaxies. A new generation of experiments and observations is now poised to address such questions from many directions at once: the Large Hadron Collider is amassing ever-larger datasets, sensitive new telescopes and detectors are mapping the cosmos with unprecedented precision, and emerging techniques ranging from intensity interferometry to quantum sensors are opening previously inaccessible windows on nature. Interpreting these data, and pointing the way toward the experiments that should come next, requires theoretical research that connects concrete models of new physics to observable signatures. It is therefore in the national interest to support theoretical work that helps the United States leverage its substantial investments in experiment and observation, promoting the progress of science in one of its most fundamental directions: the discovery of new physical laws. Under this award, Professors Ruderman and Weiner will carry out such a program, spanning laboratory, astrophysical, and cosmological probes of physics beyond the Standard Model. The project will also have significant broader impacts. The PIs will bring hands-on physics experiences to K-12 students drawn from all five boroughs of New York City through an established partnership with a public school, and will continue a fellowship that supports science-journalism students in visiting and reporting on major physics experiments. The research will additionally provide training for graduate students and postdoctoral researchers beginning careers in the field. More technically, under this award the PIs will develop and study a range of models of physics beyond the Standard Model. They will study mechanisms in which dark matter is produced through quantum-mechanical oscillations from a state in thermal equilibrium with the Standard Model plasma, including signatures of warm dark matter. They will develop an invariant, basis-independent treatment of CP violation in the Standard Model Effective Field Theory and apply it to electroweak baryogenesis, and will study how light axion-like particles affect the number of relativistic species measured by cosmic microwave background experiments. They will further develop Extended-Path Intensity Correlation, a modification of intensity interferometry that enables microarcsecond astrometry. They will also investigate whether dark matter interacting with dark radiation can address cosmological tensions in the Hubble constant and the growth of structure, and will study the coherence of dark-photon dark matter relevant to quantum-sensor searches and the halo mass function of self-interacting and dissipative dark matter. Finally, the PIs will respond to new data as it emerges to determine their theoretical implications. 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.