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managed for the U.S. Department of Energy
by Brookhaven Science Associates, a company
founded by Stony Brook University and Battelle

Background on color glass condensate

Color glass condensate is another extreme condition of matter that some theoretical physicists postulate exists inside two gold ions about to collide at very high energy in RHIC. According to Einstein’s theory of relativity, a high-energy particle appears Lorentz contracted, or compressed, along its direction of motion. As a result, the gluons inside one gold ion appear to the other ion as a ‘gluonic wall’ traveling near the speed of light. At very high energies, the density of the gluons in this wall is seen to increase greatly. Unlike the quark-gluon plasma produced in the collision of such walls, the color glass condensate describes the walls themselves, and is an intrinsic property of the particles that can only be observed under high-energy conditions such as those at RHIC.

“Color” in the name “color glass condensate” refers to a type of charge that quarks and gluons carry as a result of the strong force. The word “glass” is borrowed from the term for silica and other materials that are disordered and act like solids on short time scales but liquids on long time scales. In the “gluon walls,” the gluons themselves are disordered and do not change their positions rapidly because of Lorentz time dilation. “Condensate” means that the gluons have a very high density.

The color glass condensate (CGC) is important because it is proposed as a universal form of matter that describes the properties of all high-energy, strongly interacting particles.
It has simple properties that follow from first principles in the theory of strong interactions, quantum chromodynamics (QCD). It has the potential to explain many unsolved problems such as how particles are produced in high-energy collisions, and the distribution of matter itself inside of these particles.

There is considerable controversy among nuclear physicists about the existence of this color glass condensate and the interpretation of early experimental results coming out of RHIC, which may or may not support its existence.

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The U.S. Department of Energy's Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies. Brookhaven also builds and operates major facilities available to university, industrial, and government scientists. The Laboratory is managed by Brookhaven Science Associates, a limited liability company founded by Stony Brook University and Battelle, a nonprofit applied science and technology organization.