Dimension Seven Operators in Standard Model with Right handed Neutrinos

TL;DR

This paper systematically classifies dimension-seven operators in the Standard Model extended with right-handed neutrinos, analyzing their origins from heavy physics and deriving experimental constraints from low-energy data and LHC searches.

Contribution

It provides a complete list of gauge-invariant dimension-seven operators involving right-handed neutrinos and assesses their generation mechanisms and experimental bounds.

Findings

Identified all dimension-seven operators in the extended Standard Model.

Determined which operators can be generated at tree-level or loop-level.

Set bounds on new physics scale from low-energy and collider data.

Abstract

In this article we consider the Standard Model extended by a number of (light) right-handed neutrinos, and assume the presence of some heavy physics that cannot be directly produced, but can be probed by its low-energy effective interactions. Within this scenario, we obtain all the gauge-invariant dimension-seven effective operators, and determine whether each of the operators can be generated at tree-level by the heavy physics, or whether it is necessarily loop generated. We then use the tree-generated operators, including those containing right-handed neutrinos, to put limits on the scale of new physics $ \Lambda $ using low-energy measurements. We also study the production of same-sign dileptons at the Large Hadron Collider (LHC) and determine the constraints on the heavy physics that can be derived form existing data, as well as the reach in probing $ \Lambda $ expected from future runs of this collider.