A new presentation of the Borchers-Buchholz result of the Lorentz-invariance of the energy-momentum spectrum in theories with broken Lorentz symmetry is given in terms of properties of the Green’s functions of microcausal Bose and Fermi-fields. Strong constraints based on complex geometry phenomenons are shown to result from the interplay of the basic principles of causality and stability in Qu...

We analyze the role of Lorentz symmetry in the perturbative non-gravitational anomalies for a single family of fermions. The theory is assumed to be translational invariant, power-counting renormalizable and based on a local action, but is allowed to have general Lorentz violating operators. We study the conservation of global and gauge currents associate with general internal symmetry groups a...

The possibility that Lorentz symmetry is violated in gravitational processes is relatively unconstrained by experiment, in stark contrast with the level of accuracy to which Lorentz symmetry has been confirmed in the matter sector. One model of Lorentz violation in the gravitational sector is Einstein-aether theory, in which Lorentz symmetry is broken by giving a vacuum expectation value to a d...

Lorentz violation is a promising candidate signal for Planck-scale physics [1]. For instance, it could arise in string theory [2] and is a basic feature of noncommutative field theories [3]. In quantum field theory at attainable energies, small violations can be incorporated into the standard model to yield a general Lorentzviolating standard-model extension [4]. Its lagrangian consists of all ...

The formulation and some experimental implications of a general Lorentz-violating extension of the standard model are reviewed. The theory incorporates both CPT-preserving 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 gau...

We present a classification, up to isomorphisms, of all the homogeneous spaces of the Lorentz group with dimension lower than six. At the same time, we classify, up to conjugation, all the non-discrete closed subgroup of the Lorentz group and all the subalgebras of the Lorentz Lie algebra. We also study the covariant mappings between some pairs of homogeneous spaces. This exercise is done witho...

We present two new measurements constraining Lorentz and CPT violation using the Xe/He Zeeman maser and atomic hydrogen masers. Experimental investigations of Lorentz and CPT symmetry provide important tests of the framework of the standard model of particle physics and theories of gravity. The two-species Xe/He Zeeman maser bounds violations of CPT and Lorentz symmetry of the neutron at the 10...

We propose a reformulation of general relativity by making the Abelian decomposition of Einstein’s theory. Based on the view that Einstein’s theory can be interpreted as a gauge theory of Lorentz group, we decompose the Einstein’s gravitational connection (the gauge potential of Lorentz group Γμ) into the restricted connection made of the potential of the maximal Abelian subgroup H of Lorentz g...

We consider the radiation emitted by an ultrarelativistic charged particle moving in a magnetic field, in the presence of an additional Lorentz-violating interaction. In contrast with prior work, we treat a form of Lorentz violation that is represented by a renormalizable operator. Neglecting the radiative reaction force, the particle’s trajectory can be determined exactly. The resulting orbit ...