Color-glass condensate

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The color-glass condensate is a form of matter that is believed to exist in atomic nuclei that move at almost the speed of light . According to Einstein's theory of relativity , such a core appears length-contracted in the direction of movement , so that the gluons look like a wall for a stationary observer, moving at almost the speed of light. The density of this gluon wall increases sharply at high energies. In contrast to the quark-gluon plasma , which is generated such walls in the collision, the color-glass condensate describes these walls themselves as intrinsic property that only at high energies as at RHIC or LHC will be achieved, observed can.

The term color refers to a type of charge that quarks and gluons carry due to their strong nuclear force. The term glass is used to refer to the term for silicates and other disordered materials that behave like solids on short time scales but like liquids on long time scales . This is the case with gluon walls, because the gluons present in them are disordered, but do not change their position quickly due to the time dilation . Condensate refers to the fact that the gluons have a very high density.

The relevance of the color-glass condensate arises from the fact that it is proposed as a universal form of matter that describes properties for all high-energy, strongly interacting particles. It has simple properties that result from the principles of quantum chromodynamics . This could lead to some problems that have not yet been resolved, such as B. the generation of particles in high-energy collisions and the distribution of matter in these particles are explained.

Researchers at CERN suspect that the collision of protons with ionized lead produced such color-glass condensates. In this type of collision, the normal case is that new particles are created and fly away in different directions. In two million such proton-ion collisions, however, researchers of the CMS experiment observed a few pairs of particles that flew apart in opposite directions, with the respective directions being correlated. This correlation of directions is an anomaly that could be caused by the existence of color-glass condensates during the collision.

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Individual evidence

  1. ↑ a b CMS collaboration see Compact Muon Solenoid : Observation of long-range near-side angular correlations in proton-lead collisions at the LHC . In: Physics Letters B . 718, No. 3, September, pp. 795-814. arxiv : 1210.5482v2 . doi : 10.1016 / j.physletb.2012.11.025 .