Observational Constraints on Local Lorentz Invariance

Abstract

Local Lorentz invariance is a fundamental spacetime symmetry in the standard model of particle physics and in general relativity. However, in a quantum theory of gravity, mechanisms have been found to arise that might allow small violations of Lorentz invariance to occur. An effective field theory known as the standard model extension has been developed to search for these violations. The standard model extension incorporates Lorentz-violating interaction terms involving particle fields and gravitational fields, and it includes all terms that could arise from a process of spontaneous Lorentz violation as well as terms that explicitly break Lorentz symmetry. In this chapter, an overview of the standard model extension is presented, including its motivations and construction. A partial survey of high-precision experimental tests of local Lorentz invariance for the different particle sectors in the standard model and with gravity is presented as well.