Quantum scattering on a delta potential in ghost-free theory

Boos, Jens; Frolov, Valeri P.; Zelnikov, Andrei

doi:10.1016/j.physletb.2018.06.018

Cited by 29 publications

(28 citation statements)

References 27 publications

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“…It has the following property: In the limit when the parameter of non-locality tends to 0 it reproduces the corresponding local Hadamard function (26). It should be emphasized that in order to properly define the retarded Green function in the non-local theory one should provide a proper choice of the boundary conditions for Eq.…”

Section: "λ-Dressing" Of Hadamard Functions In the Ghost-free Theorymentioning

confidence: 99%

“…* boos@ualberta.ca † vfrolov@ualberta.ca ‡ zelnikov@ualberta.ca An alternative approach is to define the non-local quantum theory in the physical domain with Lorentz signature without ever resorting to Wick rotation. This approach was used to study radiation effects [25] by timedependent sources as well as quantum vacuum polarization effects and scattering on an external δ-potential [26,27]. Technically this approach is more involved but consistent and in accordance with the physical setup of the problem.…”

Section: Introductionmentioning

confidence: 99%

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On thermal field fluctuations in ghost-free theories

2019

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We study the response of a scalar thermal field to a δ-probe in the context of non-local ghost-free theories. In these theories a non-local form factor is inserted into the kinetic part of the action which does not introduce new poles. For the case of a static δ-potential we obtain an explicit expression for the thermal Hadamard function and use it for the calculation of the thermal fluctuations. We then demonstrate how the presence of non-locality modifies the amplitude of these fluctuations. Finally, we also discuss the fluctuation-dissipation theorem in the context of ghost-free quantum field theories at finite temperature.

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Section: "λ-Dressing" Of Hadamard Functions In the Ghost-free Theorymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

On thermal field fluctuations in ghost-free theories

2019

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“…The standard method, as it is described in section II, is not applicable to the case of the non-local ghost-free theory. However, the Lippmann-Schwinger approach works pretty well [35].…”

Section: Superradiance In the Ghost-free Scalar Theorymentioning

confidence: 99%

Superradiance in a ghost-free scalar theory

Frolov

Zelnikov

2018

Phys. Rev. D

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We study superradiance effect in the ghost-free theory. We consider a scattering of a ghost-free scalar massless field on a rotating cylinder. We assume that cylinder is thin and empty inside, so that its interaction with the field is described by a delta-like potential. This potential besides the real factor, describing its height, contains also imaginary part, responsible for the absorption of the field. By calculating the scattering amplitude we obtained the amplification coefficient both in the local and non-local (ghost-free) models and demonstrated that in the both cases it is greater than 1 when the standard superradiance condition is satisfied. We also demonstrated that dependence of the amplification coefficient on the frequency of the scalar field wave may be essentially modified in the non-local case. arXiv:1809.00417v1 [hep-th] 3 Sep 2018

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“…Computations of scattering amplitudes were performed in [48][49][50], while a detailed study of spontaneous breaking of symmetry with nonlocal interactions in [51,52]. Applications also appeared in the context of astrophysical compact objects [53,54], cosmological inflation [55], thermal field theory [56][57][58][59], supersymmetry [60,61], Hawking radiation [62], Galilean theories [63], quantum mechanics [64][65][66][67], curved Casimir effect [68] and neutrino oscillations [69].…”

Section: Introductionmentioning

confidence: 99%

Generalized ghost-free propagators in nonlocal field theories

et al. 2020

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In this paper we present an iterative method to generate an infinite class of new nonlocal field theories whose propagators are ghost-free. We first examine the scalar field case and show that the pole structure of such generalized propagators possesses the standard two derivative pole and in addition can contain complex conjugate poles which, however, do not spoil at least tree level unitarity as the optical theorem is still satisfied. Subsequently, we define analogous propagators for the fermionic sector which is also devoid of unhealthy degrees of freedom. As a third case, we apply the same construction to gravity and define a new set of theories whose graviton propagators around the Minkowski background are ghost-free. Such a wider class also includes nonlocal theories previously studied, and Einstein's general relativity as a peculiar limit. Moreover, we compute the linearized gravitational potential generated by a static point-like source for several gravitational theories belonging to this new class and show that the nonlocal nature of gravity regularizes the singularity at the origin.

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Quantum scattering on a delta potential in ghost-free theory

Cited by 29 publications

References 27 publications

On thermal field fluctuations in ghost-free theories

On thermal field fluctuations in ghost-free theories

Superradiance in a ghost-free scalar theory

Generalized ghost-free propagators in nonlocal field theories

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