Quantum forces are long-range interactions arising from quantum fluctuations of light mediator fields — either fermionic or bosonic — that couple feebly to matter. Despite their weakness, such forces can leave observable imprints in the early Universe and in precision measurements. In this talk, I will discuss quantum forces both within the Standard Model and in the dark sector.

First, the Standard Model predicts a unique quantum force mediated by the exchange of two neutrinos. Although extremely weak, this "neutrino force" can manifest in atomic systems and in backgrounds of cosmic, solar, or reactor neutrinos. I will present our recent progress in probing this effect and show that its contribution in atoms may have important implications for precision tests of the Standard Model, including low-energy determinations of the Weinberg angle.

I will then turn to quantum forces beyond the Standard Model. In the perturbative regime, I will discuss axion-mediated quantum forces and their implications for axion detection experiments. In the non-perturbative regime, I will show how quantum forces can significantly modify dark matter annihilation and self-interactions beyond the Born approximation, and discuss the resulting implications for cosmology.

Biography

Dr. Bingrong Yu is currently a postdoctoral researcher in the particle theory group at Cornell University. Before joining Cornell, he received his Ph.D. from the Institute of High Energy Physics (IHEP) in 2023 and his B.Sc. from Nanjing University in 2018. His research interests broadly span physics beyond the Standard Model, including dark matter, neutrinos, axions, early-Universe cosmology, and effective field theory. His recent work focuses on developing new ideas for probing light new physics in cosmology and in precision laboratory experiments.

Inviter: Ning-Qiang Song