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arXiv · 2001.00017

Loops and trees in generic EFTs

Nathaniel Craig·Minyuan Jiang·Ying-Ying Li·Dave Sutherland
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Abstract

We consider aspects of tree and one-loop behavior in a generic 4d EFT of massless scalars, fermions, and vectors, with a particular eye to the high-energy limit of the Standard Model EFT at operator dimensions 6 and 8. First, we classify the possible Lorentz structures of operators and the subset of these that can arise at tree-level in a weakly coupled UV completion, extending the tree/loop classification through dimension 8 using functional methods. Second, we investigate how operators contribute to tree and one-loop helicity amplitudes, exploring the impact of non-renormalization theorems through dimension 8. We further observe that many dimension 6 contributions to helicity amplitudes, including rational parts, vanish exactly at one-loop level. This suggests the impact of helicity selection rules extends beyond one loop in non-supersymmetric EFTs.

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Nathaniel Craig, Minyuan Jiang, Ying-Ying Li, Dave Sutherland. 2019-12-31. Loops and trees in generic EFTs. https://doi.org/10.1007/jhep08(2020)086

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