On (scalar QED) gravitational positivity bounds

Hamada, Yuta; Kuramochi, Rinto; Loges, Gregory J.; Nakajima, Shuro

doi:10.1007/jhep05(2023)076

Cited by 9 publications

(3 citation statements)

References 44 publications

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“…which, unless the coupling constants satisfy c ≫ b ≫ a, as we are forbidding in this section, must be solved order by order. 10 For the same reasons, we can ignore three-point vertices suppressed by Λ n for n ≥ 2. This leaves us with the following three-point vertices:…”

Section: A Maximally Natural Scenariomentioning

confidence: 99%

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Regge growth of isolated massive spin-2 particles and the Swampland

Kundu,

Palti,

Quirant

2024

J. High Energ. Phys.

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We consider an effective theory with a single massive spin-2 particle and a gap to the cutoff. We couple the spin-2 particle to gravity, and to other lower-spin fields, and study the growth of scattering amplitudes of the particle in the Regge regime: where s is much larger than t and also any mass scales in the effective theory, but still much lower than the cutoff scale of the theory and therefore any further massive spin-2 particles. We include in the effective theory all possible operators, with an arbitrary, but finite, number of derivatives. We prove that the scattering amplitude grows strictly faster than s2 in any such theory. Such fast growth goes against expected bounds on Regge growth. We therefore find further evidence for the Swampland spin-2 conjecture: that a theory with an isolated massive spin-2 particle, coupled to gravity, is in the Swampland.

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Section: A Maximally Natural Scenariomentioning

confidence: 99%

“…Some strong results on such a bound were developed in [5], for example, showing that it holds in five dimensions or higher for scattering of scalar particles. We refer to [5] for references on the topic, to [6] for a recent review, and to [7][8][9][10] for other recent work. 1…”

Section: Introductionmentioning

confidence: 99%

Regge growth of isolated massive spin-2 particles and the Swampland

Kundu,

Palti,

Quirant

2024

J. High Energ. Phys.

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“…Positivity bounds arise as part of a broader S-matrix bootstrap, which aims at mapping the space of S-matrices of all consistent quantum field theories [69,70], see also [71] for the relation of S-matrix bootstraps constraints to positivity bounds. By now positivity bounds have been derived in a variety of contexts, including without and with gravity, see, e.g., [72][73][74][75][76][77][78] and with [79][80][81][82][83][84][85][86][87] respectively, and [88] for reviews. The impact of broken Lorentz invariance has been considered in [89][90][91] and in a quantum gravitational context, positivity bounds have been considered in string theory [92][93][94].…”

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confidence: 99%

Weak-gravity bound in asymptotically safe gravity-gauge systems

2022

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The weak-gravity bound has been discovered in asymptotically safe gravity-matter systems, where it limits the maximum strength of gravitational fluctuations. In the present paper, we explore it for the first time in systems with more than one gauge field to discover whether systems with 12 gauge fields (like the Standard Model) exhibit a weak-gravity bound and whether the gravitational fixed point evades it. Further, we test the robustness of the present and previous results on the weak-gravity bound by exploring their dependence on a gravitational gauge parameter. Finally, the existence of the weak-gravity bound also has important phenomenological consequences: it is key to a proposed mechanism that bounds the spacetime dimensionality from above to four or five dimensions. In this paper, we strengthen the evidence for this mechanism. Thus, the predictive power of the asymptotic safety paradigm could extend to parameters of the spacetime geometry, such that the four dimensionality of our Universe could be explained from first principles.

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Effective field theory bootstrap, large-N χPT and holographic QCD

2024

J. High Energ. Phys.

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We review the effective field theory (EFT) bootstrap by formulating it as an infinite-dimensional semidefinite program (SDP), built from the crossing symmetric sum rules and the S-matrix primal ansatz. We apply the program to study the large-N chiral perturbation theory (χPT) and observe excellent convergence of EFT bounds between the dual (rule-out) and primal (rule-in) methods. This convergence aligns with the predictions of duality theory in SDP, enabling us to analyze the bound states and resonances in the ultra-violet (UV) spectrum. Furthermore, we incorporate the upper bound of unitarity to uniformly constrain the EFT space from the UV scale M using the primal method, thereby confirming the consistency of the large-N expansion. In the end, we translate the large-N χPT bounds to constrain the higher derivative corrections of holographic QCD models.

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On (scalar QED) gravitational positivity bounds

Cited by 9 publications

References 44 publications

Regge growth of isolated massive spin-2 particles and the Swampland

Regge growth of isolated massive spin-2 particles and the Swampland

Weak-gravity bound in asymptotically safe gravity-gauge systems

Effective field theory bootstrap, large-N χPT and holographic QCD

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