Physics & Math

The big bang machine may already be living up to its nickname. Researchers on the Compact Muon Solenoid (CMS) experiment at CERN's Large Hadron Collider near Geneva, Switzerland, have seen hints of what may be the hot, dense state of matter thought to have filled the universe in its first nanoseconds.

Quarks are generally trapped in groups of two or three by the gluons that bind them, but in the moments after the big bang, the universe was so hot that they could escape, becoming a fluid of free quarks and gluons.

A signal thought to represent this quark-gluon plasma has been seen before, following collisions between ions much heavier than the protons that the LHC smashes together. Now the CMS detector has captured a similar signal.

In snapshots from the detector, CMS collaborators noticed that some particles flying away from one another at near light speed were tracing the same angle – as if they were somehow associated.

Intriguing similarity

A similar phenomenon was seen in experiments at the Relativistic Heavy Ion Collider at Brookhaven National Laboratory (BNL) in New York, and interpreted as being due to the particles emerging from the same dense state of matter.

"The CMS results exhibit an intriguing similarity to the observations in heavy ion collisions at the Relativistic Heavy Ion Collider," says Dmitri Kharzeev of BNL. "This similarity hints at the universal properties of quark and gluon interactions at very high density."

It remains unknown whether the material that produced the correlated particles seen by the CMS collaboration was indeed a quark-gluon plasma, but the team hopes to pin this down. "What is happening may be fully understood in the next few months or year," says CMS spokesman Guido Tonelli.

Journal Reference: http://arxiv.org/abs/1009.4122

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