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managed for the U.S. Department of Energy
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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.