Lorentz-Violating Terms in Gauge Field Theorie

Our best existing description of nature is provided by the Standard Model for particle physics and General Relativity for gravity. The unification of these two theories in a consistent picture of quantum gravity is widely expected to involve modifications that go beyond known physics. One popular modification involves small deviations from Lorentz invariance. In this talk, we present all Lorentz-violating terms that can arise in a gauge field theory coupled to Dirac fermions and briefly outline some experimental implications.