quark-gluon plasma


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Related to quark-gluon plasma: Bose-Einstein condensate, Fermionic condensate

Quark-gluon plasma

A predicted state of matter containing deconfined quarks and gluons. According to the theory of strong interactions, called quantum chromodynamics, hadrons such as mesons and nucleons (the generic name for protons and neutrons) are bound states of more fundamental objects called quarks. The quarks are confined within the individual hadrons by the exchange of particles called gluons. However, calculations indicate that at sufficiently high temperatures or densities, hadronic matter should evolve into a new phase of matter containing deconfined quarks and gluons, called a quark-gluon plasma or quark matter. Such a state of matter is thought to have existed briefly in the period about 1–10 microseconds after the big bang, and might also exist inside the cores of dense neutron stars. See Hadron, Quantum chromodynamics

The study of such a new state of matter requires a means for producing it under controlled laboratory conditions. Experimentally the transition from the hadronic to the quark-gluon phase requires collisions of beams of heavy ions such as nuclei of gold or uranium (although lighter nuclei can be used) with other heavy nuclei at high enough energies to produce the necessary extreme conditions of heat and compression. Quantum chromodynamics calculations using the lattice gauge model indicate that energy densities of at least 1–2 GeV/fm3 (1 femtometer = 10-15 m), about 10 times that found in ordinary nuclear matter, must be produced in the collision for plasma formation to occur. See Nuclear reaction, Relativistic heavy-ion collisions

Accelerator experiments using beams of nuclei with energies of 10–200 GeV/nucleon bombarding stationary nuclear targets have found interesting phenomena such as nuclear stopping. In such cases, the colliding nucleons of the target and projectile are observed to pile up on each other, achieving large nuclear matter densities (two to four times normal nuclear density, or higher) corresponding to energy densities near the threshold for quark matter production. Other results of these experiments suggest that conditions favorable to thermal and chemical equilibrium may be present in some of these collisions. Such experiments can provide critical tests of the theory of the strong interaction and illuminate the earliest moments of the universe. See Elementary particle, Gluons, Quarks

quark–gluon plasma

A state of matter thought to have existed in which isolated hadrons did not exist but in which quarks and gluons formed a ‘hot soup’. It is thought that this state ended about 10–5 seconds after the big bang when there was a phase transition in which hadrons formed as the Universe cooled.

quark-gluon plasma

[′kwärk ′glü‚än ‚plaz·mə]
(nuclear physics)
A state of nuclear matter postulated by quantum chromodynamics to exist at extremely high temperatures and densities in which the neutrons and protons lose their identities and the quarks and gluons form an unstructured collection of particles.
References in periodicals archive ?
Heinz of Ohio State University in Columbus, a theorist who specializes in quark-gluon plasma.
Here, we have used equation of state for quark-gluon plasma phase with Bag value [B.sup.1/4] = 165-200 MeV and strong coupling constant [[alpha].sub.s] = 0.2.
Creating a quark-gluon plasma wasn't the aim of these experiments.
Svetitsky, "Diffusion of charmed quarks in the quark-gluon plasma," Physical Review D, vol.
Wilk, "Possible manifestation of quark-gluon plasma in multiplicity distributions from high-energy reactions," Physical Review Letters, vol.
Scientists have come up with many possible signatures of the quark-gluon plasma, but none of these alone can be considered unambiguous proof of the plasma's presence.
Next month, the new Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory in Upton, N.Y., begins its much-heralded search for the quark-gluon plasma.
Liao, "Chiral electric separation effect in the quark-gluon plasma," Physical Review D, vol.
Chirally symmetric vector mesons in the quark-gluon plasma," Physical Review D, vol.
After hearing results of recent experiments observing collisions between nuclei of lead, many were ready to take seriously the notion that such collisions could produce ultramicroscopic fireballs of quark-gluon plasma.
As a new matter state, quark-gluon plasma (QGP) is a thermalized system, which consists of strongly coupled quarks and gluons in a limited region.
One problem with making the scheme work is ensuring that the hot, low-density quark-gluon plasma created in the collision of high-speed heavy ions (SN: 10/8/88, p.229) cools in the right way to produce high-density, low-temperature drops of strange matter.