# Low-energy effective field theory below the electroweak scale: matching at one loop

## TL;DR

This paper calculates the one-loop matching conditions between the Standard Model Effective Field Theory and a low-energy effective theory below the electroweak scale, including effects up to dimension six, to aid model-independent BSM analyses.

## Contribution

It provides the complete set of one-loop matching equations for the low-energy theory, including flavor structures and CP-violating effects, extending previous work to a systematic level.

## Key findings

- Derived matching equations for masses and couplings.
- Included CP-odd and flavor-dependent effects.
- Facilitates model-independent BSM constraints.

## Abstract

We compute the one-loop matching between the Standard Model Effective Field Theory and the low-energy effective field theory below the electroweak scale, where the heavy gauge bosons, the Higgs particle, and the top quark are integrated out. The complete set of matching equations is derived including effects up to dimension six in the power counting of both theories. We present the results for general flavor structures and include both the $CP$-even and $CP$-odd sectors. The matching equations express the masses, gauge couplings, as well as the coefficients of dipole, three-gluon, and four-fermion operators in the low-energy theory in terms of the parameters of the Standard Model Effective Field Theory. Using momentum insertion, we also obtain the matching for the $CP$-violating theta angles. Our results provide an ingredient for a model-independent analysis of constraints on physics beyond the Standard Model. They can be used for fixed-order calculations at one-loop accuracy and represent a first step towards a systematic next-to-leading-log analysis.

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Source: https://tomesphere.com/paper/1908.05295