Nonlocal scalar quantum field theory from causal sets

Belenchia, Alessio; Benincasa, Dionigi M. T.; Liberati, Stefano

doi:10.1007/jhep03(2015)036

Cited by 62 publications

(85 citation statements)

References 29 publications

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“…12 Whenever there is a confusion, we will label the local quantities with a subscript L. 13 Note that Wightman function for the free-theory can get modified in field theories with non-analytic form factors, see Refs. [46,51], in our scenario this is not the case.…”

Section: Homogeneous Field Equations: Wightman Functionmentioning

confidence: 57%

“…14 It is worth mentioning that there are examples of field theories where the commutation relations for free-fields are modified by the presence of a minimal length-scale. For instance, it happens in non-commutative geometry [55] and causal-set theory [46,51]. In the latter the form factor F (k), not only depends on the invariant k 2 , but also on the sign of k 0 signaling the presence of branch-cuts in the Wightman function due to non-analyticity.…”

Section: Inhomogeneous Field Equations: Propagatormentioning

confidence: 99%

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Ghost-free infinite derivative quantum field theory

2019

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In this paper we will study Lorentz-invariant, infinite derivative quantum field theories, where infinite derivatives give rise to non-local interactions at the energy scale M s , beyond the Standard Model. We will study a specific class, where there are no new dynamical degrees of freedom other than the original ones of the corresponding local theory. We will show that the Green functions are modified by a non-local extra term that is responsible for acausal effects, which are confined in the region of non-locality, i.e. M −1 s . The standard time-ordered structure of the causal Feynman propagator is not preserved and the non-local analog of the retarded Green function turns out to be non-vanishing for space-like separations. As a consequence the local commutativity is violated. Formulating such theories in the non-local region with Minkowski signature is not sensible, but they have Euclidean interpretation. We will show how such non-local construction ameliorates ultraviolet/short-distance singularities suffered typically in the local quantum field theory. We will show that non-locality and acausality are inherently off-shell in nature, and only quantum amplitudes are physically meaningful, so that all the perturbative quantum corrections have to be consistently taken into account. (Gaetano Lambiase), anupam.mazumdar@rug.nl (Anupam Mazumdar) 1 Quadratic curvature action contains terms like R 2 , Rµν R µν , C µνρσ Cµνρσ, where µ, ν = 0, 1, 2, 3, C stands for the Weyl tensor. In 4 dimensions one can further reduce the action with the help of Gauss-Bonnet identity.

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Section: Homogeneous Field Equations: Wightman Functionmentioning

confidence: 57%

Section: Inhomogeneous Field Equations: Propagatormentioning

confidence: 99%

Ghost-free infinite derivative quantum field theory

2019

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“…In this paper we will only consider analytic form-factors. However, it is worth mentioning that nonlocal models with nonanalytic differential operators have been investigated by many authors; see, for example, Refs [59][60][61][62][63][64]…”

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confidence: 99%

Nonlocal star as a blackhole mimicker

Buoninfante

Mazumdar

2019

Phys. Rev. D

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In the context of ghost-free, infinite derivative gravity, we will provide a quantum mechanical framework in which we can describe astrophysical objects devoid of curvature singularity and event horizon. In order to avoid ghosts and singularity, the gravitational interaction has to be nonlocal, therefore, we call these objects as nonlocal stars. Quantum mechanically a nonlocal star is a selfgravitational bound system of many gravitons interacting nonlocally. Outside the nonlocal star the spacetime is well described by the Schwarzschild metric, while inside we have a non-vacuum spacetime metric which tends to be conformally flat at the origin. Remarkably, in the most compact scenario the radius of a nonlocal star is of the same order of the Buchdahl limit, therefore slightly larger than the Schwarzschild radius, such that there can exist a photosphere. These objects live longer than a Schwarzschild blackhole and they are very good absorbers, due to the fact that the number of available states is larger than that of a blackhole. As a result nonlocal stars, not only can be excellent blackhole mimickers, but can also be considered as dark matter candidates. In particular, nonlocal stars with masses below 10 14 g can be made stable compared to the age of the Universe.

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In this paper, we study the Casimir force for a class of Lorentzian nonlocal field theories [1,2]. These theories include a continuum of massive excitations.

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confidence: 99%

Casimir effect for nonlocal field theories with continuum massive modes

Saravani¹

2019

Class. Quantum Grav.

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In this paper, we study the Casimir force for a class of Lorentzian nonlocal field theories [1,2]. These theories include a continuum of massive excitations. In this regard, the effect of continuum massive modes on Casimir force is of interest. We focus on the simplest case of two absorbing parallel planes in 1+1 dimensions, and we show that, unlike local field theories, the thickness of the absorbing "walls" changes the value of Casimir force.

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Nonlocal scalar quantum field theory from causal sets

Cited by 62 publications

References 29 publications

Ghost-free infinite derivative quantum field theory

Ghost-free infinite derivative quantum field theory

Nonlocal star as a blackhole mimicker

Casimir effect for nonlocal field theories with continuum massive modes

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