质子的下一个秘密

New measurements test a decades-old hypothesis about the proton’s identity Wenliang Li The proton sits at the heart of every atom. It was once pictured as a cluster of three quarks—constituents of matter whose properties combine to produce the proton’s characteristics. Increasingly precise experiments have repeatedly challenged this classical view by revealing that a proton is not merely the sum of quarks, but a many-body system whose defining properties (such as mass and spin) arise from the collective dynamics of quarks and the gluons that bind them together (1, 2). Yet, the origin of the proton’s baryon number—a conserved quantity that distinguishes matter from antimatter—has remained elusive. …