Graviton excitations and Lorentz–Violating gravity with cosmological constant

In this work, we investigate the consequences of the spontaneous breaking of Lorentz symmetry, triggered by the bumblebee vector field, on the usual Einstein-Hilbert theory. Specifically, we consider the Einstein-Hilbert action modified by the bumblebee dynamic field, and evaluate the graviton propagator using an extended basis of Barnes-Rivers tensor projectors, involving the Lorentz-violating vector. Once the propagator is carried out, we proceed with discussing the consistency of the model, writing the dispersion relations, and analyzing causality and unitarity.We verify that this model possesses two dispersion relations: one provides causal and unitary propagating modes, while the second yields a causal but nonunitary mode which spoils the physical consistency of the model.

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“…[84]. In such an extension, the spin operators induced by the Lorentzviolating background b µ yields the whole set of structures listed below:…”

Section: Remarks and Conclusionmentioning

confidence: 99%

Einstein-Hilbert graviton modes modified by the Lorentz-violating bumblebee field

et al. 2014

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“…Possible effects of Lorentz symmetry violation have been investigated in many contexts, for example, the Casimir effect [8][9][10][11], QED [12][13][14][15][16], hydrogen atom [17,18], noncommutative field theories [19][20][21], space-times with a non-trivial topology [22], gravity theory [23][24][25][26][27][28], electromagnetic wave propagation [29][30][31][32], studies of photon field quantization [33][34][35], effects on the classical electrodynamics [36][37][38][39][40][41], among others.…”

Section: Introductionmentioning

confidence: 99%

A perfectly conducting surface in electrodynamics with Lorentz symmetry breaking

Borges

Barone

2017

Eur. Phys. J. C

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In this paper we consider a model which exhibits explicit Lorentz symmetry breaking due to the presence of a single background vector v μ coupled to the gauge field. We investigate such a theory in the vicinity of a perfectly conducting plate for different configurations of v μ . First we consider no restrictions on the components of the background vector and we treat it perturbatively up to second order. Next, we treat v μ exactly for two special cases: the first one is when it has only components parallel to the plate, and the second one when it has a single component perpendicular to the plate. For all these configurations, the propagator for the gauge field and the interaction force between the plate and a point-like electric charge are computed. Surprisingly, it is shown that the image method is valid in our model and we argue that it is a non-trivial result. We show there arises a torque on the mirror with respect to its positioning in the background field when it interacts with a point-like charge. It is a new effect with no counterpart in theories with Lorentz symmetry in the presence of a perfect mirror.

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“…On the other hand, possible Lorentzviolating (LV) extensions of the SM, standard model extensions (SME), have, apparently, no troubles both theoretically and experimentally [1,2] and many theories exhibiting Lorentz violation were proposed in recent years. We can mention the cases of the SM Electroweak sector [3], Quantum Chromodynamics [4], Quantum Electrodynamics [5], a pure Yang-Mills theory [6] and other theories [7][8][9][10][11][12][13].…”

Section: Introductionmentioning

confidence: 99%