Changes

QCD has successfully described jet events at particle colliders. In these events, a particle and antiparticle are smashed together in a collider; the resulting energy then turns into a quark and anti-quark pair. The quark and anti-quark each then split into vast, complex showers of other high-energy particles, called "jets", which are seen as showers of particles in opposing directions in the particle detector. If the quark and anti-quark produce showers immediately, it is called a two-jet event. In about 10% of all cases, a quark or anti-quark will emit a gluon, which then splits into still more particles, thus displaying a three-jet event.  QCD successfully models the probability and momentum distributions of the jets<ref>http://nobelprize.org/nobel_prizes/physics/laureates/2004/wilczek-lecture.pdf (p. 102)</ref>.

QCD has successfully described jet events at particle colliders. In these events, a particle and antiparticle are smashed together in a collider; the resulting energy then turns into a quark and anti-quark pair. The quark and anti-quark each then split into vast, complex showers of other high-energy particles, called "jets", which are seen as showers of particles in opposing directions in the particle detector. If the quark and anti-quark produce showers immediately, it is called a two-jet event. In about 10% of all cases, a quark or anti-quark will emit a gluon, which then splits into still more particles, thus displaying a three-jet event.  QCD successfully models the probability and momentum distributions of the jets<ref>http://nobelprize.org/nobel_prizes/physics/laureates/2004/wilczek-lecture.pdf (p. 102)</ref>.

Non-perturbative methods have recently been very successfully used in QCD. Lattice gauge QCD calculations, requiring vast computer power, have computed the masses of the proton, neutron<ref>S. Dürr, Z. Fodor, J. Frison, C. Hoelbling, R. Hoffmann, S. D. Katz, S. Krieg, T. Kurth, L. Lellouch, T. Lippert, K. K. Szabo, and G. Vulvert. <i>Ab Initio Determination of Light Hadron Masses.</i> and mesons<i>Science</i> 21 Vol. 322. no. 5905 (Nov. 2008), pp. 1224 - 1227. DOI: 10.1126/science.1163233.</ref><ref>C. T. Davies <i>et al.</i> <i>High-Precision Lattice QCD Confronts Experiment</i>. Phys. Rev. Lett. 92, 22001 (2004). DOI: 10.1103/PhysRevLett.92.022001. </ref>, by computing the energy of the interaction E of the quarks and gluons on a lattice, and then employing Einstein's equation m = E/c2. These calculations compute the masses of several important particles entirely a priori, with no tuneable free parameters input to the model, except the strong coupling constant.

Non-perturbative methods have recently been very successfully used in QCD. Lattice gauge QCD calculations, requiring vast computer power, have computed the masses of the proton, neutron<ref>S. Dürr, Z. Fodor, J. Frison, C. Hoelbling, R. Hoffmann, S. D. Katz, S. Krieg, T. Kurth, L. Lellouch, T. Lippert, K. K. Szabo, and G. Vulvert. <i>Ab Initio Determination of Light Hadron Masses.</i> and mesons<i>Science</i> 21 Vol. 322. no. 5905 (Nov. 2008), pp. 1224 - 1227. DOI: 10.1126/science.1163233.</ref><ref>C. T. Davies <i>et al.</i> <i>High-Precision Lattice QCD Confronts Experiment</i>. Phys. Rev. Lett. 92, 22001 (2004). DOI: 10.1103/PhysRevLett.92.022001. </ref>, by computing the energy of the interaction E of the quarks and gluons on a lattice, and then employing Einstein's equation m = E/c2. These calculations compute the masses of several important particles entirely ''[[a priori]],'' with no tuneable free parameters input to the model, except the strong coupling constant.

== Field Theory and Relativity ==

== Field Theory and Relativity ==