For many years strong interactions had a well-deserved reputation for complexity. Their apparent strength rendered perturbation theory inapplicable. However, in the late 1960s a series of experiments studying the deep inelastic electron–nucleon scattering showed that at a more fundamental level, the strong interactions among the constituent quarks can be described perturbatively by an asymptotically free gauge theory. We present the theory of quantum chromodynamics, the unbroken gauge theory of the colour SU(3) group. We show how we can compute its predictions in the kinematic regions in which perturbation theory is applicable, but also in the strong coupling regime through numerical simulations on a space-time lattice.
Constraining dark matter-nucleon scattering cross section by the background electron anti-neutrino flux data
