Gravitational field of static 
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-branes in linearized ghost-free gravity

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

doi:10.1103/physrevd.97.084021

Cited by 77 publications

(84 citation statements)

References 51 publications

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“…The corresponding modification implies the introduction of the form factor in the kinetic part of the auxiliary field. The corresponding non-local action takes the form (20)- (21). We obtained an expression for the non-local modification of the effective action, calculated the corresponding stressenergy tensor, and studied its dependence on the state described by zero modes of the -operator.…”

Section: Discussionmentioning

confidence: 99%

Ghost-free modification of the Polyakov action and Hawking radiation

2019

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In this paper we discuss possible effects of non-locality in black hole spacetimes. We consider a two-dimensional theory in which the action describing matter is a ghost-free modification of the Polyakov action. For this purpose we write the Polyakov action in a local form by using an auxiliary scalar field and modify its kinetic term by including into it a non-local ghost-free form factor. We demonstrate that the effective stress-energy tensor is modified and we study its properties in a background of a two-dimensional black hole. We obtain the expression for the contribution of the ghost-free auxiliary field to the entropy of the black hole. We also demonstrate that if the backreaction effects are not taken into account, such a ghost-free modification of the theory does not change the energy flux of the Hawking radiation measured at infinity. We illustrate the discussed properties for black hole solution of a 2D dilaton gravity model which admits a rather complete analytical study.

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Section: Discussionmentioning

confidence: 99%

Ghost-free modification of the Polyakov action and Hawking radiation

2019

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“…[20] for a more general treatment including some non-maximally symmetric spacetime. It was also noticed that the presence of nonlocality can regularize infinities and many efforts have been made towards the resolution of black hole [17,18,[21][22][23][24][25][26][27][28][29][30][31][32][33] and cosmological [16,[34][35][36][37] singularities. At the quantum level, the high energy behavior of loop integrals has been investigated in [38][39][40][41] and properties of causality and unitarity in [42,43] and [44][45][46][47], respectively.…”

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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“…Scenarios like this have also appeared in the literature in many string inspired realizations in order to avoid the information-loss paradox [22,[25][26][27]. Hence, despite the simplicity of the model, we will be able to capture the main features of nonlocality which turn out to be universal and we believe will also hold in a more realistic astrophysical scenarios.Let us consider a nonlocal massless scalar field Φ interacting with a potential V in 1 + 1 dimensions with a nonlocal operator given by an exponential of an entire function(1) we will work with the simplest kinetic operator above but other choices are also possible [4,14,17,18]. In Eq.…”

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“…(1) we will work with the simplest kinetic operator above but other choices are also possible [4,14,17,18]. In Eq.…”

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Nonlocality amplifies echoes

2019

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In this paper we will provide smoking-gun signatures of nonlocal interactions while studying reflection and transmission of waves bouncing through two Dirac delta potentials. In particular, we will show that the transmission of waves is less damped compared to the local case, due to the fact that nonlocality weakens the interaction. As a consequence the echoes are amplified. These signatures can be potentially detectable in the context of gravitational waves, where two Dirac delta potentials can mimic the two potential barriers at the surface and at the photon sphere of an ultra compact object, or, at the two photon spheres of a wormhole, experiencing nonlocal interactions.The nonlocal interactions have been widely studied since the days of Yukawa [1], Pias and Uhlenbeck [2]. It has been studied widely in the context of quantum field theory in order to ameliorate the ultraviolet (UV) (or, in other words, short-distance) behavior of loop integrals and scattering amplitudes [3][4][5][6]. One of the striking features of nonlocality is that it weakens the interaction, and as a direct consequence it can regularize singularities through smearing out a point-like Dirac delta distribution [7][8][9][10]. The simplest nonlocal interaction can be captured by infinite derivative field theories, where the kinetic operator is generalized by means exponentials of entire functions, which do not introduce any new dynamical degrees of freedom, and modifies the UV behavior of the theory. The latter criteria guarantees perturbative unitarity and classical stability which, in general, are absent in any finite higher derivative theory, see [4,9,10,12]. All these interesting results have inspired the generalization of the Einstein-Hilbert action for gravity to infinite derivative gravity (IDG), with form factors containing nonlocal operators in order to make the theory well defined both at classical and quantum level [4,[7][8][9][10]13]. In a recent generalization which contains all possible curvature corrections [10], it was shown that IDG can resolve the point-like singularity in a static [10,11,[16][17][18], and the ring singularity in a rotating spacetime metric [15], and with the presence of torsion as well [19]. In a dynamical collapse also there are no formation of horizon and singularities [20]. Furthermore, such gravitational actions also help in order to understand the cosmological Big Bang singularity problem [9,21], and potentially resolving the event horizon in the context of astrophysical compact objects [22].The aim of this paper is to provide a smoking gun signature for nonlocal interactions. In particular, we will study the propagation of waves in nonlocal massless scalar field theory in presence of two Dirac delta potential barriers in one spatial dimension. We will work out the quasi-normal modes (QNMs) and the echoes of an initial incoming pulse and make the comparison with the local case. Our analysis allows to make a very powerful analogy in astrophysics. First of all, the two Dirac deltas can be used to model the...

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Gravitational field of static p -branes in linearized ghost-free gravity

Cited by 77 publications

References 51 publications

Ghost-free modification of the Polyakov action and Hawking radiation

Ghost-free modification of the Polyakov action and Hawking radiation

Generalized ghost-free propagators in nonlocal field theories

Nonlocality amplifies echoes

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