Multi-charged TeV scale scalars and fermions in the framework of a radiative seesaw model

TL;DR

This paper proposes a collider-testable radiative seesaw model with multi-charged scalars and fermions at the TeV scale, explaining neutrino masses and mixings, and analyzes its collider signatures and experimental bounds.

Contribution

It introduces a novel radiative seesaw model without extra symmetries, featuring multi-charged particles at TeV scale, and studies their collider phenomenology and experimental constraints.

Findings

Constraints from neutrino oscillation data are satisfied.

Bounds on long-lived multi-charged particles from ATLAS are derived.

Proposed 4-lepton event selection enhances signal detection.

Abstract

Explaining the tiny neutrino masses and non-zero mixings have been one of the key motivations for going beyond the framework of the Standard Model (SM). We discuss a collider testable model for generating neutrino masses and mixings via radiative seesaw mechanism. That the model does not require any additional symmetry to forbid tree-level seesaws makes its collider phenomenology interesting. The model includes multi-charged fermions/scalars at the TeV scale to realize the Weinberg operator at 1-loop level. After deriving the constraints on the model parameters resulting from the neutrino oscillation data as well as from the upper bound on the absolute neutrino mass scale, we discuss the production, decay and resulting collider signatures of these TeV scale fermions/scalars at the Large Hadron Collider (LHC). We consider both Drell-Yan and photoproduction. The bounds from the neutrino data indicate the possible presence of a long-lived multi-charged particle (MCP) in this model. We obtain bounds on these long-lived MCP masses from the ATLAS search for abnormally large ionization signature. When the TeV scale fermions/scalars undergo prompt decay, we focus on the 4-lepton final states and obtain bounds from different ATLAS 4-lepton searches. We also propose a 4-lepton event selection criteria designed to enhance the signal to background ratio in the context of this model.