Lattice QCD

Lattice QCD

In physics, lattice quantum chromodynamics (lattice QCD) is a theory of quarks and gluons formulated on a space-time lattice. That is, it is a lattice model of quantum chromodynamics, a special case of a lattice gauge theory or lattice field theory. At the moment, this is the most well established non - perturbative approach to solving the theory of Quantum Chromodynamics. Analytic or perturbative solutions in QCD are hard or impossible due to the highly nonlinear nature of the strong force. The formulation of QCD on a discrete rather than continuous space-time naturally introduces a momentum cut off at the order 1/a, which regularizes the theory. As a result lattice QCD is mathematically well-defined. Most importantly, lattice QCD provides the framework for investigation of non-perturbative phenomena such as confinement and quark-gluon plasma formation, which are intractable by means of analytic field theories.

In lattice QCD spacetime is represented not as continuous but as a crystalline lattice, vertices connected by lines. Quarks may reside only on vertices and gluons can only travel along lines. While this is understood to be a fiction, the hope is that as the spacing between vertices is reduced to zero, or to the Planck length, the theory will yield meaningful results.

This technique is only applicable in the domain of low density and high temperature; at higher densities, the region alas of greatest interest, the fermion sign problem renders the results useless. Lattice QCD predicts that confined quarks will become released to quark-gluon plasma around energies of 170 MeV. Lattice QCD's limitation to low density does not allow investigation of the color flavor locked states (CFL) at higher densities.

Lattice QCD has already made contact with experiments at various fields with good results. A particular important tool of the theory showing the confinement of the underlying fields is the Wilson loop variable, described in a separate article.

References


*Creutz, Michael "Quarks, Gluons and Lattices" (Cambridge, 1983)
*Wilson, K.G., and Kogut, J., "Lattice Gauge Theory ...", Rev. Mod. Phys. 55 , 775 (1983)
*Degrand and De Tar "Lattice Methods for Quantum Chromodynamics" (World Scientific, 2006)
*Montvay and Münster "Quantum Fields on a Lattice" (Cambridge 1997)

ee also

* Lattice gauge theory
* Quark-gluon plasma
* QCD matter

External links

* [http://arxiv.org/abs/hep-lat/9807028 Gupta - Introduction to Lattice QCD]
* [http://arxiv.org/abs/hep-lat/0509180 Lombardo - Lattice QCD at Finite Temperature and Density]
* [http://arxiv.org/abs/hep-lat/0405024 Chandrasekharan, Wiese - An Introduction to Chiral Symmetry on the Lattice]


Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать реферат

Look at other dictionaries:

  • International Workshops on Lattice QCD and Numerical Analysis — The International Workshops on Lattice QCD and Numerical Analysis first started in 1995. The aim is to bring together applied mathematicians and theoretical physicists as well as to stimulate the exchange of ideas between leading experts in the… …   Wikipedia

  • QCD vacuum — The QCD vacuum is the vacuum state of quantum chromodynamics (QCD). It is an example of a non perturbative vacuum state, characterized by many non vanishing condensates such as the gluon condensate or the quark condensate. These condensates… …   Wikipedia

  • QCD matter — Quark matter or QCD matter (see QCD) refers to any of a number of theorized phases of matter whose degrees of freedom include quarks and gluons. These theoretical phases would occur at extremely high temperatures and densities, billions of times… …   Wikipedia

  • Lattice gauge theory — In physics, lattice gauge theory is the study of gauge theories on a spacetime that has been discretized onto a lattice. Although most lattice gauge theories are not exactly solvable, they are of tremendous appeal because they can be studied by… …   Wikipedia

  • QCD — Die Quantenchromodynamik (QCD) ist die quantenfeldtheoretische Beschreibung der starken Wechselwirkung. Inhaltsverzeichnis 1 Einleitung 2 Nichtabelsche Eichgruppe 3 Erläuterungen und Abgrenzung zur Kernphysik 4 Lagrangedichte der QCD …   Deutsch Wikipedia

  • Lattice field theory — In physics, lattice field theory is the study of lattice models of quantum field theory, that is, of field theory on a spacetime that has been discretized onto a lattice. Although most lattice field theories are not exactly solvable, they are of… …   Wikipedia

  • QCD string — In quantum chromodynamics, or more generally, quantum gauge theories with a connection which are confining, stringlike degrees of freedom called QCD strings or QCD flux tubes form. These stringlike excitations are responsible for the confinement… …   Wikipedia

  • Lattice model (physics) — For other meanings, see lattice model (disambiguation) In physics, a lattice model is a physical model that is defined on a lattice, as opposed to the continuum of space or spacetime. Lattice models originally occurred in the context of condensed …   Wikipedia

  • Quantum chromodynamics — Standard model of particle physics Standard Model …   Wikipedia

  • Gittereichtheorie — Eine Gittereichtheorie ist eine Eichtheorie, welche auf einer diskreten Raumzeit definiert wird. Gittereichtheorien gehören zu den wenigen Möglichkeiten nicht störungstheoretische Berechnungen in Quantenfeldtheorien durchzuführen. Die Grundidee… …   Deutsch Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”