Universal Scalar Leptoquark Action for Matching

TL;DR

This paper develops a universal one-loop effective action framework for scalar leptoquarks, enabling precise matching to SMEFT and facilitating future automated calculations of relevant observables.

Contribution

It introduces a universal effective action for scalar leptoquark matching using covariant diagrams and supertrace evaluation, applicable to various models and operators.

Findings

Validated the method with a model including scalar leptoquarks.

Calculated observables like lepton dipole moments and neutrino masses.

Demonstrated the approach's utility for EFT benchmarks and future automation.

Abstract

In this study we present a universal effective action for one-loop matching of all scalar leptoquarks. We use both the Universal One-Loop Effective Action (UOLEA) and covariant diagrams to evaluate the Wilson coefficients directly in the Green basis for up-to dimension-6 operators. On the technical side, we use the newly developed method of evaluating supertraces, to further validate the results stemming from the use of covariant diagrams. As an application, we perform a fully functional matching onto Standard Model Effective Field Theory (SMEFT) of a model with two scalar leptoquark fields: a weak isospin singlet and a doublet. We demonstrate its use by calculating several observables, such as lepton magnetic and electric dipole moments, neutrino masses, proton decay rate, while we comment upon fine tuning issues in this model. Apart from its phenomenological interest, this model generates the majority of dimension-6 operators and provides an EFT benchmark towards future matching automation.