Experimental Constraints on Higgs Boson Decays to TeV-scale Right-Handed Neutrinos

Abstract

The existence of neutrino masses strongly suggests that right-handed neutrinos exist, but the data do not favor any particular scale for the Majorana mass parameters. Here I explore the possibility that these particles exist at the electroweak scale along with additional new physics at the TeV scale . Higher dimension operators involving right-handed neutrinos and the Higgs boson can introduce new decay modes of the Higgs boson, significantly modifying its phenomenology if it is light. With minimal flavor violation the Higgs boson cascade decays to 6 particles containing two highly displaced vertices. Each displaced vertex produces an odd number of leptons, leading to a dramatic signature of overall lepton violation at each vertex. I discuss the limits from the Tevatron, and find that they are close to exploring interesting regions of parameters, while limiting others. Moving beyond minimal flavor violation, cascade decays of the Higgs boson into as many as 14 particles can occur.