General Neutrino Interactions from an Effective Field Theory Perspective

TL;DR

This paper systematically embeds general neutrino interactions within an effective field theory framework, exploring their correlations, bounds, and possible UV completions, with implications for various processes and new physics scenarios.

Contribution

It provides a comprehensive gauge-invariant operator basis for GNI, maps these to observable parameters, and discusses their UV completions via leptoquarks, extending the understanding of neutrino interactions.

Findings

Mapped GNI parameters to effective operators respecting SM gauge symmetry

Analyzed correlations and bounds from charged lepton flavor violation and scattering

Explored UV completions via leptoquarks related to neutrino masses and B anomalies

Abstract

General Neutrino Interactions (GNI) are scalar, pseudoscalar, vector, axial vector or tensor interactions of neutrinos with fermions, and generalise the often studied neutrino Non-Standard Interactions (NSI). If GNI arise from heavy new physics, they should be embeddable into effective field theory operators that respect the Standard Model (SM) gauge symmetry. Therefore we consider a full basis of gauge-invariant dimension-six operators involving SM fermions and right-handed singlet neutrinos and map their Wilson coefficients onto GNI parameters. In this embedding we discuss correlations of and bounds on different GNI in the context of charged lepton flavour violation processes and neutrino-fermion scattering, as well as beta decay and coherent neutrino-nucleus scattering. We also study possible UV completions of the relevant dimension-six operators for GNI via leptoquarks that can be related to radiative neutrino masses and $B$ physics anomalies. Details on the numbers of free GNI parameters for Dirac or Majorana neutrinos and for CP violation or conservation are also provided.