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arXiv · 2507.08803

Infra-red enhanced loops in quadratic gravity

Alberto Salvio·Alessandro Strumia·Marco Vitti
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Abstract

It has been suggested that logarithmically enhanced infra-red loop corrections arising in theories with four derivatives correspond to a physical running of couplings, rendering quadratic gravity asymptotically free. We find that these effects depend on the gauge and on the field parameterisation. We compute physical on-shell amplitudes and find genuine infra-red log-enhanced loop corrections, that are process-dependent and cannot be absorbed into running couplings. As a byproduct, we derive the effective action of quadratic gravity at tree level, showing that its ghost does not contribute to effective operators and thereby does not violate positivity bounds.

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Alberto Salvio, Alessandro Strumia, Marco Vitti. 2025-07-11. Infra-red enhanced loops in quadratic gravity. https://arxiv.org/abs/2507.08803

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