Unitarity in higher-order Lorentz-invariance violating QED

Reyes, Carlos M.

doi:10.1103/physrevd.87.125028

Cited by 62 publications

(27 citation statements)

References 50 publications

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“…This theoretical framework has inspired a large number of investigations in the last several years, encompassing fermion systems [12][13][14][15][16][17][18][19][20], CPT-probing experiments [21][22][23][24][25][26][27], the electromagnetic CPT-and Lorentzodd term [28]- [41], the CPT-even and Lorentz-odd gauge sector and its interactions with fermions [42][43][44][45][46][47][48][49][50][51], [52][53][54][55][56][57]. Recent investigations involving higher dimensional operators [58][59][60], its possible connections with LV theories [61][62][63][64][65][66], and nonminimal couplings [67][68][69][70]…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2014

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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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Section: Introductionmentioning

confidence: 99%

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

et al. 2014

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“…We checked that the solution (15) indeed corresponds to a minimum of the effective potential (12). An interesting point to note is that the dynamical mass (15) is analytic in the coupling constant g 2 , unlike the situation of Lifshitz 4-fermion interaction [7,19], where a dynamical mass has the typical non-analytic form…”

Section: Massless Model and Dynamical Mass Generationmentioning

confidence: 92%

“…More general Lorentz-and CPT-violating terms with arbitrary mass dimension have been studied and classified in [9] and [10], in the photon and neutrino sectors, respectively. There are also studies considering perturbative and non-perturbative properties of specific LIV higher order operators, for examples see [11] and [12]. Moreover, some studies regarding Lorentz violation in the neutrino sector whether considering higher order operators or not have been performed, many of them regarding neutrino oscillations, such as [13] and [14].…”

Section: Introductionmentioning

confidence: 99%

Quasirelativistic fermions and dynamical flavor oscillations

Alexandre

Leite²,

Mavromatos

2014

Phys. Rev. D

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We introduce new Lorentz-symmetry violating kinematics for a four-fermion interaction model, where dynamical mass generation is allowed, irrespectively of the strength of the coupling. In addition, these kinematics lead to a quasi-relativistic dispersion relation, in the sense that it is relativistic in both the infrared and the ultraviolet, but not in an intermediate regime, characterized by the mass M. For two fermions, we show that a flavour-mixing mass matrix is generated dynamically, and the Lorentz symmetric limit M → ∞ leads to two free relativistic fermions, with flavour oscillations. This model, valid for either Dirac or Majorana fermions, can describe any set of phenomenological values for the eigen masses and the mixing angle.

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“…In quantum field theory, Lee and Wick showed that by imposing the negative norm states to decay it is possible to preserve unitarity order by order in perturbation theory [44,45]. Resurgence of such ideas have been used to solve the hierarchy problem [19,20] and in higher-order effective models with Lorentz symmetry violation [46][47][48].…”

Section: Introductionmentioning

confidence: 99%

Polymer quantization, stability and higher-order time derivative terms

Eltit

Reyes

Ossandón

2016

Int. J. Mod. Phys. A

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The possibility that fundamental discreteness implicit in a quantum gravity theory may act as a natural regulator for ultraviolet singularities arising in quantum field theory has been intensively studied. Here, along the same expectations, we investigate whether a nonstandard representation, called polymer representation can smooth away the large amount of negative energy that afflicts the Hamiltonians of higher-order time derivative theories; rendering the theory unstable when interactions come into play. We focus on the fourthorder Pais-Uhlenbeck model which can be reexpressed as the sum of two decoupled harmonic oscillators one producing positive energy and the other negative energy. As expected, the Schrödinger quantization of such model leads to the stability problem or to negative norm states called ghosts. Within the framework of polymer quantization we show the existence of new regions where the Hamiltonian can be defined well bounded from below.

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Unitarity in higher-order Lorentz-invariance violating QED

Cited by 62 publications

References 50 publications

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

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

Quasirelativistic fermions and dynamical flavor oscillations

Polymer quantization, stability and higher-order time derivative terms

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