Tree-level scattering amplitudes in nonlocal field theories

Modesto, Leonardo; Calcagni, Gianluca

doi:10.1007/jhep10(2021)169

Cited by 14 publications

(7 citation statements)

References 59 publications

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“…However, we expect the same results listed above to apply according to the mass dimension of the coupling constant involved in the scattering process. The asymptotic freedom [46,47] in super-renormalizable theories [5,7,9] or the softness of the quantum amplitudes in finite theories [6,8,10,11] guarantee the stability and Universality of our result in a consistent theory of all fundamental interactions [10,11,48].…”

Section: Summary and Discussionmentioning

confidence: 98%

“…However, at large distances 1/r 3 is sub-leading with respect to the classical counterpart 1/r. We expect that higher-loops contributions will also not spoil the conditions (i)-(ii) because of the asymptotic freedom [46,47] in super-renormalizable theories [5,7,9] or the softness of the quantum amplitudes in finite theories [6,8,10,11,48].…”

Section: Jhep07(2022)131mentioning

confidence: 99%

“…(a) are the same as the local standard model coupled to gravity [48] so that the classical limit is recovered for f (t) = 1. Let us shortly remind the theory in [10,11,48],…”

Section: Jhep07(2022)131mentioning

confidence: 99%

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Stringballs and Planckballs for dark matter

Zhongyou

Netto

Burzillà

et al. 2022

J. High Energ. Phys.

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As a follow up of the seminal work by Guiot, Borquez, Deur, and Werner on “Graviballs and Dark Matter”, we explicitly show that in string theory, local and nonlocal higher derivative theories, as well as general asymptotically-free or finite theories, gravitationally interacting bound states can form when the energy is larger than the Planck energy. On the other hand, in higher derivative or nonlocal theories with interaction governed by a dimensionless or a dimensionful coupling constant, the bound states form when the energy is smaller than the Planck energy. Such bound states are allowed because of the softness of the scattering amplitudes in the ultraviolet region. Indeed, in such theories, the potential is finite while the force is zero or constant in r = 0. Finally, since the bound states that form in the early Universe may have an energy that ranges from the Planck mass to any arbitrarily large or small value, we argue that they can serve as dark matter candidates and/or as the seeds for the structure’s formation at large scale in the Cosmos.

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Section: Summary and Discussionmentioning

confidence: 98%

Section: Jhep07(2022)131mentioning

confidence: 99%

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Stringballs and Planckballs for dark matter

Zhongyou

Netto

Burzillà

et al. 2022

J. High Energ. Phys.

Self Cite

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“…UV-completion in string theory. Other particularities are: (i) the tree-level scattering amplitudes are identical to the ones of the mother local QFT [105], with the same causal properties [106]; (ii) any solution of the classical field equations of the mother local theory is also solution of the nonlocal one. Such properties do not hold in the class of string-inspired nonlocal scalar theory [33] studied in our article.…”

Section: Discussionmentioning

confidence: 99%

Fate of the false vacuum in string-inspired nonlocal field theory

Ghoshal

Nortier

2022

J. Cosmol. Astropart. Phys.

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In this article, we study Coleman bounce in weakly nonlocal theories which are motivated from string field theory. The kinetic term is extended via an infinite series of high-order derivatives, which comes into play at an energy scale M, without introducing any new states or ghosts in the mass spectrum. We calculate the bubble nucleation in thin-wall approximation, treating the system in semi-classical manner. We find that the effect of nonlocal scale M in the theory is to suppress the vacuum tunneling rate from false to true vacuum compared to the standard local bouncing scenario. Likewise, we show that as we move further away from the bubble wall, the effects of nonlocality gets reduced and this suppression is significant only around the wall of the nucleated bubble. From our investigations, we conclude that the main effect is due to the fact that the nonlocality smears the solution of the local bubble profile. However, the energy of the bubble wall remains unaffected by the microscopic nonlocal behavior of the theory in the thin-wall approximation. We also discuss the cases for Lee-Wick theories and applications of our result to cosmology.

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“…The second example is non-local quantum gravity with asymptotically polynomial operators, which is super-renormalizable or even finite depending on whether one adds killer operators or not. Also in this case the graviton tree-level scattering amplitudes diverge as E 2 at E → +∞ [151,155] but this theory is known to be perturbatively unitary at all orders [141]. The energy divergence is a non-issue because, once perturbative unitarity is proven, it must be preserved also at the level of the fully resummed scattering amplitudes.…”

Section: Jcap09(2023)003mentioning

confidence: 99%

Ultraviolet-complete quantum field theories with fractional operators

Calcagni,

Rachwał

2023

J. Cosmol. Astropart. Phys.

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We explore quantum field theories with fractional d'Alembertian □ γ . Both a scalar field theory with a derivative-dependent potential and gauge theory are super-renormalizable for a fractional power 1 < γ ≤ 2, one-loop super-renormalizable for γ > 2 and finite if one introduces killer operators. Unitarity is achieved by splitting the kinetic term into the product of massive fractional operators, eventually sending the masses to zero if so desired. Fractional quantum gravity is also discussed and found to be super-renormalizable for 2 < γ ≤ 4 and one-loop super-renormalizable for γ > 4. To make it unitary, we combine the splitting procedure with a fractional generalization of the Anselmi-Piva procedure for fakeons. Among new technical results with wider applications, we highlight the Leibniz rule for arbitrary powers of the d'Alembertian and the Källén-Lehmann representation for a propagator with an arbitrary number of branch cuts.

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Tree-level scattering amplitudes in nonlocal field theories

Cited by 14 publications

References 59 publications

Stringballs and Planckballs for dark matter

Stringballs and Planckballs for dark matter

Fate of the false vacuum in string-inspired nonlocal field theory

Ultraviolet-complete quantum field theories with fractional operators

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