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arXiv 1902.032502019-02hep-thgr-qchep-ph

Amplitudes' Positivity, Weak Gravity Conjecture, and Modified Gravity

Brando Bellazzini, Matthew Lewandowski, Javi Serra

备注：: v4: two more appendices, discussion of Froissart bound extended
发表信息：: Phys. Rev. Lett. 123, 251103 (2019)
DOI：: 10.1103/PhysRevLett.123.251103

英文摘要：

We derive new positivity bounds for scattering amplitudes in theories with a massless graviton in the spectrum in four spacetime dimensions, of relevance for the weak gravity conjecture and modified gravity theories. The bounds imply that extremal black holes are self-repulsive, $M/|Q|<1$ in suitable units, and that they are unstable to decay to smaller extremal black holes, providing an S-matrix proof of the weak gravity conjecture. We also present other applications of our bounds to the effective field theory of axions, $P(X)$ theories, weakly broken galileons, and curved spacetimes.

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