Hunting for heavy composite Majorana neutrinos at the LHC

TL;DR

This paper explores the potential to discover heavy Majorana neutrinos from a composite model at the LHC, emphasizing the dominance of contact interactions over gauge interactions in production rates, and assessing the discovery reach through simulated signatures.

Contribution

It introduces the significance of contact interactions in composite Majorana neutrino production at the LHC, expanding beyond previous gauge interaction-focused studies.

Findings

Contact interactions dominate production cross sections by two to three orders of magnitude.

Potentially larger excluded regions at 13 TeV compared to Run I.

Provides 3σ and 5σ significance contours for parameter space.

Abstract

We investigate the search for heavy Majorana neutrinos stemming from a composite model scenario at the upcoming LHC Run II at a center of mass energy of 13 TeV. While previous studies of the composite Majorana neutrino were focussed on gauge interactions via magnetic type transition coupling between ordinary and heavy fermions (with mass $m^*$) here we complement the composite model with contact interactions at the energy scale $\Lambda$ and we find that the production cross sections are dominated by such contact interactions by roughly two/three orders of magnitude. This mechanism provides therefore very interesting rates at the prospected luminosities. We study the same sign di-lepton and di-jet signature ($pp \to \ell\ell jj$) and perform a fast detector simulation based on Delphes. We compute 3$\sigma$ and 5$\sigma$ contour plots of the statistical significance in the parameter space ($\Lambda,m^*$). We find that the potentially excluded regions at $\sqrt{s} =13$ TeV are quite larger than those excluded so far at Run I considering searches with other signatures.