D. Marchand

A beam of electrons, twisted like a corkscrew, slams into a proton. From the collision point, pairs of particles, a positive and a neutral pion, fly out. For the first time, physicists measured how often such pairs scatter at different angles when the electron's spin points left or right.

At the Jefferson Lab accelerator, a beam of light strikes protons, and the collisions give birth to short-lived particles — omega mesons. They live for less than a billionth of a second, but they still manage to tell us about the forces inside the atomic nucleus.