Understanding Charged-Particle Bound States in Periodic Boxes

Physicists use methods called finite-volume simulations with periodic boundary conditions to model the nuclei protons and neutrons can form. This new work solves a long-standing and fundamental problem for electrically charged systems in these “periodic boxes.” It derives the mathematical equation that describes how the properties of these electrically charged systems depend on the size of the simulation volume.

Decoding the Proton’s Response to an External Electromagnetic Field

The proton is the only composite building block of matter that is stable in nature, making its properties key to understanding the formation of matter. A team of physicists measured the proton’s electric polarizability, which characterizes the proton’s susceptibility to deformation, or its “stretchability,” in the presence of a photon’s electromagnetic field. The results reveal a puzzling new structure – a bump in the polarizability that nuclear theory cannot explain.