November 27, 2012
Collisions between protons and lead ions at the Large Hadron Collider (LHC) have produced surprising behavior in some of the particles created by the collisions. The new observation suggests the collisions may have produced a new type of matter known as color-glass condensate.
When beams of particles crash into each other at high speeds, the collisions yield hundreds of new particles, most of which fly away from the collision point at close to the speed of light. However, the Compact Muon Solenoid (CMS) team at the LHC found that in a sample of 2 million lead-proton collisions, some pairs of particles flew away from each other with their respective directions correlated. “Somehow they fly at the same direction even though it’s not clear how they can communicate their direction with one another.
That has surprised many people, including us,” says MIT physics professor Gunther Roland, whose group led the analysis of the collision data along with Wei Li, a former MIT postdoc who is now an assistant professor at Rice University. A paper describing the unexpected findings will appear in an upcoming issue of the journal Physical Review B and is now available on arXiv.