Abstract
In this paper, we discuss the potential of observing heavy neutrino (νh) signatures of a U(1)B−L enlarged Standard Model (SM) encompassing three heavy Majorana neutrinos alongside the known light neutrino states at the Large Hadron Collider (LHC). We exploit the theoretical decay via a heavy (non-SM-like) Higgs boson and Z′ production followed by νh → l±W∓(∗) and νh → νlZ(∗) decays, ultimately yielding a 3l + 2j + ETmiss signature and, depending upon how boosted the final state objects are, we define different possible selections aimed at improving the signal to background ratio in LHC Run 2 data for a wide range of heavy neutrino masses.
Highlights
A particular feature of such a heavy neutrino pair signature is that decay width of the heavy neutrino is small and its lifetime large, so that it turns out to be a long-lived particle and, over a large portion of the U(1)B−L parameter space, its lifetime can be such that it can decay inside the Large Hadron Collider (LHC) detectors, producing a distinctive Displaced Vertices (DVs) signature
Our conclusion is that this analysis, carried out with standard techniques, requires very high luminosity and is tailored for the High Luminosi√ty Large Hadron Collider (HL-LHC)
We explore an advanced experimental strategy based on the so called fat jet. This attempt relies on the observation that the two produced jets are quite collimated, giving rise to a unique large hadronic cone, owing either to the boosted heavy neutrino (BP1) or to the boosted W -boson coming from the heavy neutrino decay (BP2)
Summary
We deal with a minimal renormalisable Abelian extension of the SM with only the matter content necessary to satisfy the cancellation of all gauge and gravitational anomalies. The existence of a scalar field generating the Majorana mass for RH neutrinos through a Yukawa coupling, which is a characteristic feature of the Abelian extensions of the SM, allows for the new and interesting possibility of producing a heavy neutrino pair from the SM-like Higgs (besides the obvious heavy Higgs mode). The interaction between the light SM-like Higgs and the heavy neutrinos is not suppressed by the mixing angle Vαi but is controlled by the Yukawa coupling YN and scalar mixing angle α. For illustrative purposes we assume that the PMNS matrix is equal to the identity matrix and that both neutrino masses, light and heavy, are degenerate in flavour In this case the elements of the neutrino mixing matrix Vαi are given by mD/M ≃
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