Proton put through the looking glass

摘要

When Alice went through the looking glass, a world of surprises awaited. Not so for the proton. For the first time, physicists have measured how this building block of matter feels the weak force, the only force that treats particles and their mirror images differently. The team at the Thomas Jefferson National Accelerator Facility in Newport News, Virginia, fired electrons at target protons while switching the electrons' spins between clockwise and its mirror image, counterclockwise.