Positivity restrictions on the mixing of dimension-eight SMEFT operators Rodríguez Chala, Mikael Li, Xue Zeng We discuss the structure of the mixing among dimension-eight operators in the Standard Model effective field theory relying on the positivity of two-to-two forward scattering amplitudes. We uncover tens of new nontrivial zeros as well as hundreds of terms with definite sign in (a particular basis of) the corresponding anomalous dimension matrix. We highlight that our results are not immediately apparent from the Feynman diagrammatic perspective, nor from on-shell amplitude methods. As a by-product of this work, we provide positivity bounds not previously derived in the literature, as well as explicit values of certain elements of the anomalous dimension matrix that serve as a cross-check of our results. 2024-06-07T07:27:59Z 2024-06-07T07:27:59Z 2024-03-13 journal article Mikael Chala and Xu Li. Positivity restrictions on the mixing of dimension-eight SMEFT operators. Phys. Rev. D 109, 065015 (2024) [10.1103/PhysRevD.109.065015] https://hdl.handle.net/10481/92411 10.1103/PhysRevD.109.065015 eng info:eu-repo/grantAgreement/EC/NextGenerationEU/CNS2022-136024 http://creativecommons.org/licenses/by/4.0/ open access Atribución 4.0 Internacional American Physical Society