## Saturday, November 03, 2012

### "Ridges" In High-Energy Collisions

It looks like Ruffles potato chips are not the only ones that have ridges.

New results out of the CMS detector at the LHC seems to produce "ridge"-like structure in the collision data between proton-lead. This observation has been detected before.

The first data from proton–lead collisions at the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC) at CERN include a "ridge" structure in correlations between newly generated particles. According to theorists in the US, the ridge may represent a new form of matter known as a "colour glass condensate".

This is not the first time such correlations have been seen in collision remnants – in 2005, physicists working on the Relativistic Heavy-Ion Collider (RHIC) at Brookhaven National Laboratory in New York found that the particles generated in collisions of gold nuclei had a tendency to spread transversely from the beam at very small relative angles, close to zero. A similar correlation was seen in 2010 at CMS in proton–proton collisions and then later that year in lead–lead collisions.
Of course, as expected, theorists are already out in force presenting various scenarios to explain this phenomenon. We simply have to wait for more data to come in before we can make any kind of rational decision on this.

Zz.