Jet substructure shedding light on heavy Majorana neutrinos at the LHC

TL;DR

This paper introduces a novel jet substructure technique to detect heavy Majorana neutrinos at the LHC, focusing on the signature of same sign leptons and a fat-jet, enhancing search sensitivity for neutrino masses between 300 and 800 GeV.

Contribution

The study proposes a new jet substructure method for identifying heavy Majorana neutrinos, improving detection prospects over existing approaches at the LHC.

Findings

Effective exploration of neutrino masses 300-800 GeV.

Potential to surpass current LHC and electroweak bounds.

Enhanced sensitivity with high luminosity data.

Abstract

The existence of tiny neutrino masses and flavor mixings can be explained naturally in various seesaw models, many of which typically having additional Majorana type SM gauge singlet right handed neutrinos ($N$). If they are at around the electroweak scale and furnished with sizeable mixings with light active neutrinos, they can be produced at high energy colliders, such as the Large Hadron Collider (LHC). A characteristic signature would be same sign lepton pairs, violating lepton number, together with light jets -- $pp\to N\ell^{\pm}, \; N\to\ell^{\pm}W^{\mp}, \; W^{\mp}\to jj$. We propose a new search strategy utilising jet substructure techniques, observing that for a heavy right handed neutrino mass $M_N$ much above $M_{W^\pm}$, the two jets coming out of the boosted $W^\pm$ may be interpreted as a single fat-jet ($J$). Hence, the distinguishing signal topology will be $\ell^{\pm}\ell^{\pm} J$. Performing a comprehensive study of the different signal regions along with complete background analysis, in tandem with detector level simulations, we compute statistical significance limits. We find that heavy neutrinos can be explored effectively for mass ranges $300$ GeV $\leq M_N \leq 800$ GeV and different light-heavy neutrino mixing $|V_{\mu N}|^{2}$. At the 13 TeV LHC with 3000 $\mathrm{fb}^{-1}$ integrated luminosity one can competently explore mixing angles much below present LHC limits, and moreover exceed bounds from electroweak precision data.