Editing Quantum chromodynamics (section)

===Lattice QCD===
{{main|Lattice QCD}}
[[Image:Fluxtube meson.png|right|thumb|150px|{{langle}}''E''<sup>2</sup>{{rangle}} plot for static quark–antiquark system held at a fixed separation, where blue is zero and red is the highest value (result of a lattice QCD simulation by M. Cardoso et al.<ref>{{cite journal |first1=M. |last1=Cardoso |first2=N. |last2=Cardoso |first3=P. |last3=Bicudo |display-authors=1 |title=Lattice QCD computation of the colour fields for the static hybrid quark–gluon–antiquark system, and microscopic study of the Casimir scaling |journal=Phys. Rev. D |volume=81 |issue= 3|pages=034504 |year=2010 |doi=10.1103/PhysRevD.81.034504 |arxiv=0912.3181 |bibcode=2010PhRvD..81c4504C |s2cid=119216789 }}</ref>)]]
Among non-perturbative approaches to QCD, the most well established is [[lattice QCD]]. This approach uses a discrete set of spacetime points (called the lattice) to reduce the analytically intractable path integrals of the continuum theory to a very difficult numerical computation that is then carried out on [[supercomputers]] like the [[QCDOC]], which was constructed for precisely this purpose. While it is a slow and resource-intensive approach, it has wide applicability, giving insight into parts of the theory inaccessible by other means, in particular into the explicit forces acting between  quarks and antiquarks in a meson.   However, the [[numerical sign problem]] makes it difficult to use lattice methods to study QCD at high density and low temperature (e.g. nuclear matter or the interior of neutron stars).