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arXiv · 2607.18398

The fermion sector of the SMEFT from asymptotically safe gravity

Astrid Eichhorn·Moritz Gessner·Shouryya Ray
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Abstract

Quantum gravity impacts Standard Model fields through effective interactions generated by renormalization. These appear as Standard Model Effective Field Theory (SMEFT) operators, where the effects of new physics are parametrized by the values of the higher-order SMEFT coefficients. As a step towards predicting these SMEFT coefficients from the asymptotically safe Standard Model with quantum gravity, we investigate the flow of a representative set of four-fermion operators under gravitational fluctuations. We strengthen the evidence for the near-perturbative nature of asymptotic safety by finding that these dimension-six-interactions remain irrelevant, resulting in the prediction of specific values for the dimensionless ratios of SMEFT coefficients in the IR. We also find a mechanism that can make a specific subset of these operators relevant. This subset is determined by symmetry considerations. On this basis, we provide a categorization of dimension-six-SMEFT interactions into two categories. Interactions in the first category are predicted to be non-zero, but Planck-scale suppressed. Interactions in the second category are predicted to be zero at small gravitational coupling, but may become free parameters of the theory at larger gravitational couplings.

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Astrid Eichhorn, Moritz Gessner, Shouryya Ray. 2026-07-20. The fermion sector of the SMEFT from asymptotically safe gravity. https://arxiv.org/abs/2607.18398

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