Photon-photon scattering from a UV-complete gravity QFT

Abstract

Quantum quadratic gravity (QQG) produces a tree-level differential cross section for $\gamma \gamma \to \gamma \gamma$ that is well-behaved at all energies. From this we can study how the corrections to low energy scattering amplitudes are related to the UV physics, in particular to the exchange of the massive graviparticles. An effective forward scattering amplitude is obtained by separating out the effects of the $t$-channel graviton pole. This is possible due to the UV-completeness, and even though the Froissart bound is not satisfied. We then consider photon-photon scattering to two graviparticles and a further imaginary contribution to the $\gamma \gamma \to \gamma \gamma$ forward scattering amplitude. Unitarity without positivity is a key property of QQG and it impacts all our results.

arXiv comment14 pages, no figures

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• Ultra-Planckian quark and gluon scattering in agravity
• Strict renormalizability as a paradigm for fundamental physics
• Quantum gravity phenomenology from the perspective of quantum general relativity and quadratic gravity
• On the physical running of the electric charge in a dimensionless theory of gravity
• Leading singularities in higher-derivative Yang-Mills theory and quadratic gravity
• Scattering amplitudes in dimensionless quadratic gravity coupled to QED