Universal scalar leptoquark action for matching

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.

Automated summary

This study presents a universal effective action for one-loop matching of all scalar leptoquarks, using UOLEA and covariant diagrams to evaluate Wilson coefficients directly. The technical approach includes using the newly developed method of evaluating supertraces to further validate results. The model with two scalar leptoquark fields is used as an application, performing a full matching onto SMEFT and calculating various observables, highlighting its phenomenological interest and providing an EFT benchmark for future automation.