Probing the Weinberg Operator at Colliders

TL;DR

This paper explores how collider experiments, specifically the LHC, can probe the Weinberg operator related to neutrino masses through non-resonant same-sign dilepton signatures, extending beyond nuclear decay searches.

Contribution

It develops a new method to test the Weinberg operator at colliders, focusing on the muon channel, and estimates the sensitivity reach for new physics scales.

Findings

LHC can probe scales up to 8.3 TeV with 300 fb^{-1}.

The effective Majorana mass for muons can be constrained to around 5-7 GeV.

Provides a framework for collider tests of the Weinberg operator.

Abstract

Motivated by searches for $0\nu\beta\beta$ decay in nuclear experiments and collider probes of lepton number violation at dimension $d\geq7$, we investigate the sensitivity to the $d=5$ Weinberg operator using the non-resonant signature $pp\to \ell^\pm \ell'^{\pm} j j$ at the LHC. We develop a prescription for the operator that is applicable in collisions and decays, and focus on the $\ell\ell'=\mu\mu$ channel, which is beyond the reach of nuclear decays. For a Wilson coefficient $C^{\mu\mu}_5=1$, scales as heavy as $\Lambda\sim 8.3~(11)$~TeV can be probed with $\mathcal{L}=300~{\rm fb}^{-1}~(3~{\rm ab}^{-1})$. This translates to an effective $\mu\mu$ Majorana mass of $\vert m_{\mu\mu}\vert\sim7.3~(5.4)$~GeV, and establishes a road map for testing the Weinberg operator at accelerators.