Coordinated motion observed in debris from lead-proton collisions
Strangely behaving subatomic particles at the world’s most powerful particle accelerator could lead to fresh insight into how matter behaves at the smallest scales and highest energies.
Ordinarily, the Large Hadron Collider near Geneva sends protons hurtling into each other at velocities approaching the speed of light. But for several hours in September, the machine collided protons into lead nuclei — tightly packed bundles of 82 protons and 126 neutrons. It was merely a test run, designed to calibrate instruments for future experiments.
But when physicists with the Compact Muon Solenoid collaboration analyzed the data, they quickly noticed that something was amiss. When a proton and lead nucleus collide, they shatter into smaller particles that jet out in all directions. The movement of each piece of shrapnel should be almost completely random; the direction of one particle should provide no clue to that of any other. Yet during these collisions, the pa