THE STANDARD-MODEL EXTENSION AND TESTS OF RELATIVITY
Neil Russell · 2008
The Standard-Model Extension, or SME, is a general framework for the study of Lorentz violation in physics. A broad variety of experiments is able to access the SME coefficient space. This proceedings briefly summarizes theory and experiments aimed at testing Special Relativity by measuring these coefficients. Lorentz symmetry is a central feature of the existing theories of gravitation and particle physics. The existence of highly sensitive experiments with the ability to test Lorentz symmetry at unprecedented levels raises the possibility of discovering unconventional effects. This is clearly of interest to physicists since it may pave the way to finding a unified theory of quantum gravity. A series of publications since 1989 has established a framework, the Standard-Model Extension, or SME, that provides a detailed description of possible Lorentz violations in nature in the context of effective field theory. At the basic level, this work focuses on a variety of theoretical issues, including string theory, and spontaneous symmetry breaking. 1 Much theoretical and experimental effort has been directed towards the study of Lorentz symmetry in Minkowski space, for which the effective field theory is an extension of the Standard Model of particle physics. In flat spacetime, the SME comprises a broad variety of constant coefficients for Lorentz violation that can in principle be measured. 2 These coefficients transform as conventional Lorentz tensors under observer transformations, but under rotations and boosts of experimental systems, called particle transformations, they are not transformed.