Physics is also called "high-energy physics" because many elementary particles do not occur naturally but are created only during high-energy collisions of other particles. Currently, the interactions of elementary particles and fields are described by the Standard Model. The model accounts for the 12 known particles of matter (quarks and leptons) that interact via the strong, weak, and electromagnetic fundamental forces. Dynamics are described in terms of matter particles exchanging gauge bosons (gluons, W and Z bosons, and photons, respectively). The Standard Model also predicts a particle known as the Higgs boson. In July 2012 CERN, the European laboratory for particle
Technicolor (physics) "M", and the coupling of quarks and leptons to the new particles must be suppressed relative to their coupling to the gauge bosons. This is the case with technicolor, so long as the lightest technivector mesons, "ρ" and "a", are heavier than 200–300 GeV. The "S"-parameter is sensitive to all new physics at the TeV scale, while "T" is a measure of weak-isospin breaking effects. The "U"-parameter is generally not useful; most new-physics theories, including technicolor theories, give negligible contributions to it. The "S" and "T"-parameters are determined by global fit to experimental data including "Z"-pole data from LEP at