Color glass condensate
Encyclopedia
The color glass condensate is an extreme type of matter
theorized to exist in atomic nuclei travelling near the speed of light
.
According to Einstein’s theory of relativity
, a high-energy nucleus appears length contracted
, or compressed, along its direction of motion
. As a result, the gluon
s inside the nucleus appear to a stationary observer
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 quark
s and gluons carry as a result of the strong nuclear force. The word "glass
" is borrowed from the term for silica and other materials that are disordered and act like solid
s on short time scales but liquid
s on long time scale
s. In the "gluon walls," the gluons themselves are disordered and do not change their positions rapidly because of time dilation
. "Condensate" means that the gluons have a very high density.
The color glass condensate 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
. 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.
Matter
Matter is a general term for the substance of which all physical objects consist. Typically, matter includes atoms and other particles which have mass. A common way of defining matter is as anything that has mass and occupies volume...
theorized to exist in atomic nuclei travelling near the speed of light
Speed of light
The speed of light in vacuum, usually denoted by c, is a physical constant important in many areas of physics. Its value is 299,792,458 metres per second, a figure that is exact since the length of the metre is defined from this constant and the international standard for time...
.
According to Einstein’s theory of relativity
Theory of relativity
The theory of relativity, or simply relativity, encompasses two theories of Albert Einstein: special relativity and general relativity. However, the word relativity is sometimes used in reference to Galilean invariance....
, a high-energy nucleus appears length contracted
Length contraction
In physics, length contraction – according to Hendrik Lorentz – is the physical phenomenon of a decrease in length detected by an observer of objects that travel at any non-zero velocity relative to that observer...
, or compressed, along its direction of motion
Motion (physics)
In physics, motion is a change in position of an object with respect to time. Change in action is the result of an unbalanced force. Motion is typically described in terms of velocity, acceleration, displacement and time . An object's velocity cannot change unless it is acted upon by a force, as...
. As a result, the gluon
Gluon
Gluons are elementary particles which act as the exchange particles for the color force between quarks, analogous to the exchange of photons in the electromagnetic force between two charged particles....
s inside the nucleus appear to a stationary observer
Frame of reference
A frame of reference in physics, may refer to a coordinate system or set of axes within which to measure the position, orientation, and other properties of objects in it, or it may refer to an observational reference frame tied to the state of motion of an observer.It may also refer to both an...
as a 'gluonic wall' traveling near the speed of light. At very high energies, the density
Density
The mass density or density of a material is defined as its mass per unit volume. The symbol most often used for density is ρ . In some cases , density is also defined as its weight per unit volume; although, this quantity is more properly called specific weight...
of the gluons in this wall is seen to increase greatly. Unlike the quark-gluon plasma
Quark-gluon plasma
A quark–gluon plasma or quark soup is a phase of quantum chromodynamics which exists at extremely high temperature and/or density. This phase consists of asymptotically free quarks and gluons, which are several of the basic building blocks of matter...
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 quark
Quark
A quark is an elementary particle and a fundamental constituent of matter. Quarks combine to form composite particles called hadrons, the most stable of which are protons and neutrons, the components of atomic nuclei. Due to a phenomenon known as color confinement, quarks are never directly...
s and gluons carry as a result of the strong nuclear force. The word "glass
Glass
Glass is an amorphous solid material. Glasses are typically brittle and optically transparent.The most familiar type of glass, used for centuries in windows and drinking vessels, is soda-lime glass, composed of about 75% silica plus Na2O, CaO, and several minor additives...
" is borrowed from the term for silica and other materials that are disordered and act like solid
Solid
Solid is one of the three classical states of matter . It is characterized by structural rigidity and resistance to changes of shape or volume. Unlike a liquid, a solid object does not flow to take on the shape of its container, nor does it expand to fill the entire volume available to it like a...
s on short time scales but liquid
Liquid
Liquid is one of the three classical states of matter . Like a gas, a liquid is able to flow and take the shape of a container. Some liquids resist compression, while others can be compressed. Unlike a gas, a liquid does not disperse to fill every space of a container, and maintains a fairly...
s on long time scale
Time scale
A time scale specifies divisions of time.*Time standard, a specification of either the rate at which time passes, or points in time, or both*Duration , a quantity of time...
s. In the "gluon walls," the gluons themselves are disordered and do not change their positions rapidly because of time dilation
Time dilation
In the theory of relativity, time dilation is an observed difference of elapsed time between two events as measured by observers either moving relative to each other or differently situated from gravitational masses. An accurate clock at rest with respect to one observer may be measured to tick at...
. "Condensate" means that the gluons have a very high density.
The color glass condensate 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
Quantum chromodynamics
In theoretical physics, quantum chromodynamics is a theory of the strong interaction , a fundamental force describing the interactions of the quarks and gluons making up hadrons . It is the study of the SU Yang–Mills theory of color-charged fermions...
. 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.