Heavy Majorana neutrino pair productions at the LHC in minimal U(1) extended Standard Model

TL;DR

This paper investigates the potential for discovering heavy Majorana neutrinos at the LHC within a minimal U(1) extended Standard Model, highlighting enhanced production rates and the possibility of detection before the $Z'$ boson.

Contribution

It provides a comprehensive parameter scan showing the maximum production rate of Majorana neutrinos at the LHC, including an alternative charge assignment that further enhances discovery prospects.

Findings

Enhanced branching ratio of $Z'$ to RHNs increases detection chances.

Possibility of discovering RHNs before $Z'$ at future LHC runs.

Parameter space allows for significant same-sign dilepton signals.

Abstract

In our recent paper [1], we explored a prospect of discovering the heavy Majorana right-handed neutrinos (RHNs) at the future LHC in the context of the minimal non-exotic U(1) extended Standard Model (SM), where a pair of RHNs are created via decay of resonantly produced massive U(1) gauge boson ($Z^{\prime}$). We pointed out that this model can yield a significant enhancement of the branching ratio of the $Z^\prime$ boson to a pair of RHNs, which is crucial for discovering the RHNs under the very severe LHC Run-2 constraint from the search for the $Z^\prime$ boson with dilepton final states. In this paper, we perform a general parameter scan to evaluate the maximum production rate of the same-sign dilepton final states (smoking gun signature of Majorana RHNs production) at the LHC, while reproducing the neutrino oscillation data. We also consider the minimal non-exotic U(1) model with an alternative charge assignment. In this case, we find a further enhancement of the branching ratio of the $Z^\prime$ boson to a pair of RHNs compared to the conventional case, which opens up a possibility of discovering the RHNs even before the $Z^\prime$ boson at the future LHC experiment.