Tree-level UV completions for $N_R$SMEFT $d=6$ and $d=7$ operators

TL;DR

This paper systematically classifies tree-level ultraviolet completions for dimension-6 and dimension-7 operators in the $N_R$SMEFT, focusing on those involving right-handed neutrinos, and explores their implications for LNV processes and neutrino masses.

Contribution

It provides a comprehensive, diagrammatic enumeration of possible UV models for $N_R$SMEFT operators at $d=6$ and $d=7$, extending previous SMEFT analyses.

Findings

Generated lists of UV completions involving scalars, fermions, or vectors.

Compared UV models for $N_R$SMEFT with those for pure SMEFT.

Discussed the connection between LNV processes at LHC and Majorana neutrino masses.

Abstract

We study ultra-violet completions for operators in standard model effective field theory extended with right-handed neutrinos ($N_R$SMEFT). Using a diagrammatic method, we generate systematically lists of possible tree-level completions involving scalars, fermions or vectors for all operators at $d=6$ and $d=7$, which contain at least one right-handed neutrino. We compare our lists of possible UV models to the ones found for pure SMEFT. We also discuss how the observation of LNV processes via $N_R$SMEFT operators at the LHC can be related to Majorana neutrino masses of the standard model neutrinos.