# Search for a heavy composite Majorana neutrino in the final state with two leptons and two quarks at sqrt(s) = 13 TeV

## TL;DR

This paper reports a search for heavy composite Majorana neutrinos in proton-proton collisions at 13 TeV, setting new exclusion limits up to around 4.7 TeV, and finds data consistent with the standard model.

## Contribution

First experimental search for heavy composite Majorana neutrinos at the LHC, establishing exclusion limits up to 4.7 TeV for the neutrino mass.

## Key findings

- No significant deviation from the standard model observed.
- Excluded the existence of N(e) and N(mu) up to 4.60 and 4.70 TeV.
- Set first limits on heavy composite Majorana neutrino masses.

## Abstract

A search for physics beyond the standard model in the final state with two same-flavour leptons (electrons or muons) and two quarks produced in proton-proton collisions at sqrt(s) = 13 TeV is presented. The data were recorded by the CMS experiment at the CERN LHC and correspond to an integrated luminosity of 2.3 inverse femtobarns. The observed data are in good agreement with the standard model background prediction. The results of the measurement are interpreted in the framework of a recently proposed model in which a heavy Majorana neutrino, N(l), stems from a composite-fermion scenario. Exclusion limits are set for the first time on the mass of the heavy composite Majorana neutrino, m[N(l)], and the compositeness scale Lambda. For the case m[N(l)] = Lambda, the existence of N(e) (N(mu)) is excluded for masses up to 4.60 (4.70) TeV at 95% confidence level.