Lorentz and CPT Violating Chern-Simons Term in the Formulation of Functional Integral

We show that in the functional integral formalism the (finite) coefficient of the induced, Lorentz- and CPT-violating Chern-Simons term, arising from the Lorentz- and CPT-violating fermion sector, is undetermined.Comment: 5 pages, no figure, RevTe

Kinematical solution of the UHE-cosmic-ray puzzle without a preferred class of inertial observers

Among the possible explanations for the puzzling observations of cosmic rays above the GZK cutoff there is growing interest in the ones that represent kinematical solutions, based either on general formulations of particle physics with small violations of Lorentz symmetry or on a quantum-gravity-motivated scheme for the breakup of Lorentz symmetry. An unappealing aspect of these cosmic-ray-puzzle solutions is that they require the existence of a preferred class of inertial observers. Here I propose a new kinematical solution of the cosmic-ray puzzle, which does not require the existence of a preferred class of inertial observers. My proposal is a new example of a type of relativistic theories, the so-called "doubly-special-relativity" theories, which have already been studied extensively over the last two years. The core ingredient of the proposal is a deformation of Lorentz transformations in which also the Planck scale $E_p$ (in addition to the speed-of-light scale $c$) is described as an invariant. Just like the introduction of the invariant $c$ requires a deformation of the Galileian transformations into the Lorentz transformations, the introduction of the invariant $E_p$ requires a deformation of the Lorentz transformations, but there is no special class of inertial observers. The Pierre Auger Observatory and the GLAST space telescope should play a key role in future developments of these investigations. I also emphasize that the doubly-special-relativity theory here proposed, besides being the first one to provide a solution for the cosmic-ray puzzle, is also the first one in which a natural description of macroscopic bodies is achieved, and may find applications in the context of a recently-proposed dark-energy scenario.Comment: LaTex (revtex), 9 page

Testing CPTCPT invariance with the neutral-DD system

We investigate the issue of testing $CPT$ invariance in the neutral-$D$ system, using $D$ events obtained either from fixed-target experiments or from a $\tau$-charm factory. For both types of experiments we show that the expected suppression of mixing in the $D$ system, normally viewed as a disadvantage for $CP$ tests, allows unsuppressed measurement of certain parameters describing $CPT$ violation. Asymmetries are presented that permit the extraction of parameters for direct $CPT$ violation in the $D$ system and for indirect $CPT$ violation in the $K$ system. We also show that experiments on the neutral-$D$ system provide an alternative means for measuring conventional indirect $T$ violation in the kaon system

Analogue Models for T and CPT Violation in Neutral-Meson Oscillations

Analogue models for CP violation in neutral-meson systems are studied in a general framework. No-go results are obtained for models in classical mechanics that are nondissipative or that involve one-dimensional oscillators. A complete emulation is shown to be possible for a two-dimensional oscillator with rheonomic constraints, and an explicit example with spontaneous T and CPT violation is presented. The results have implications for analogue models with electrical circuits.Comment: 9 page

Superfield Realizations of Lorentz and CPT Violation

Superfield realizations of Lorentz-violating extensions of the Wess-Zumino model are presented. These models retain supersymmetry but include terms that explicitly break the Lorentz symmetry. The models can be understood as arising from superspace transformations that are modifications of the familiar one in the Lorentz-symmetric case.Comment: 10 page

Spin dependent masses and Sim(2) symmetry

Recently, Cohen and Glashow pointed out that all known experimental tests of relativistic kinematics are consistent with invariance of physics under the four-parameter subgroup Sim(2) of the Lorentz group. The massive one-particle irreducible representations of ISim(2), that is Sim(2) times spacetime translations, are all one-dimensional, labeled by spin along a preferred axis. Consequently particle theories based on this symmetry can accomodate lepton number conserving masses for left-handed neutrinos without the need to introduce sterile states. The same property of massive particle representations, however, also leads to the possibility that particle masses may be split within the diffferent spins of a representation of the ordinary Poincare group. In this article we investigate the low-energy structure of theories with spin dependent masses and comment on the bounds on such effects.Comment: 6 page

Exact calculation of the radiatively-induced Lorentz and CPT violation in QED

Radiative corrections arising from the axial coupling of charged fermions to a constant vector b_\mu can induce a Lorentz- and CPT-violating Chern-Simons term in the QED action. We calculate the exact one-loop correction to this term keeping the full b_\mu dependence, and show that in the physically interesting cases it coincides with the lowest-order result. The effect of regularization and renormalization and the implications of the result are briefly discussed.Comment: LaTex, 8 pages; minor correction

Velocity in Lorentz-Violating Fermion Theories

We consider the role of the velocity in Lorentz-violating fermionic quantum theory, especially emphasizing the nonrelativistic regime. Information about the velocity will be important for the kinematical analysis of scattering and other problems. Working within the minimal standard model extension, we derive new expressions for the velocity. We find that generic momentum and spin eigenstates may not have well-defined velocities. We also demonstrate how several different techniques may be used to shed light on different aspects of the problem. A relativistic operator analysis allows us to study the behavior of the Lorentz-violating Zitterbewegung. Alternatively, by studying the time evolution of Gaussian wave packets, we find that there are Lorentz-violating modifications to the wave packet spreading and the spin structure of the wave function.Comment: 24 page

Possible Spontaneous Breaking of Lorentz and CPT Symmetry

One possible ramification of unified theories of nature such as string theory that may underlie the conventional standard model is the possible spontaneous breakdown of Lorentz and CPT symmetry. In this talk, the formalism for inclusion of such effects into a low-energy effective field theory is presented. An extension of the standard model that includes Lorentz- and CPT-breaking terms is developed. The restriction of the standard model extension to the QED sector is then discussed.Comment: Talk presented at Non-Accelerator New Physics, Dubna, Russia, July 199