Testing a CPT- and Lorentz-Violating Extension of the Standard Model

Abstract

The formulation and some experimental implications of a general Lorentz-violating extension of the standard model are reviewed. The theory incorporates both CPTpreserving and CPT-breaking terms. It is otherwise a conventional quantum field theory, obtained under the assumption that Lorentz symmetry is spontaneously broken in an underlying model. The theory contains the usual standard-model gauge structure, and it is power-counting renormalizable. Energy and momentum are conserved. Despite the violation of Lorentz symmetry, the theory exhibits covariance under Lorentz transformations of the observer inertial frame. A general Lorentz-violating extension of quantum electrodynamics can be extracted. The standard-model extension implies potentially observable effects in a wide variety of experiments, including among others measurements on neutral-meson oscillations, comparative studies in Penning traps, spectroscopy of hydrogen and antihydrogen, bounds on cosmological birefringence, measurements of muon properties, clock-comparison tests, and observations of the baryon asymmetry.1 Invited talk at the conference Beyond the Standard Model,

Robust constraint on Lorentz violation using Fermi-LAT gamma-ray burst data

“…7 by downward-(upward-)pointing triangles. For every realization we apply the kurtosis estimation procedure to a set of 16 thousand toys generated with the energy smearing procedure described earlier, to obtain the optimal values of the compensation parameters 18 . The final distribution of the recovered value of the compensation parameter τ recov for a particular amount of injected dispersion τ true is obtained as the average over all 15 realizations within a single set.…”

“…Studies exhibiting similar levels of sensitivity have also been performed elsewhere [29,30] [28] for a discussion of the definition of measurable momenta in such models. 7 In field-theoretical models such as the Standard Model Extension [6,18,19] in which Lorentz invariance is broken spontaneously, there are also birefringence effects. Probes of the rotation of the polarization of light from distant astrophysical sources [21,22] constrain this effect very strongly [23][24][25][26][27].…”

“…These include purely phenomenological models motivated by aspects of cosmic-ray physics [16] and other considerations [17]. A more theoretical suggestion -the 'Standard Model Extension' -is the possibility that Lorentz invariance is broken spontaneously [6,18,19], and it has been argued in the context of some models of loop quantum gravity [5] that the vacuum might exhibit non-trivial optical properties. Moreover, quantum field theories of the Lifshitz type [20], in which the space and time coordinates scale differently, have attracted renewed interest in the context of quantum gravity.…”

A 3+1 Decomposition of the Gravitational Sector of the Minimal Standard-Model Extension

“…1 The Standard-Model Extension (SME) is an often-used effective field theory framework which includes all Lorentz and CPT violating terms. [2][3][4] The 3+1 (ADM) version of GR is used in for example canonical quantum gravity and numerical relativity. 5,6 Here we present a 3+1 decomposition of the minimal SME gravity Lagrangian in the case of explicit Lorentzsymmetry breaking.…”