Abstract: Results are presented of a search for a heavy Majorana neutrino Image 1 decaying into two same-flavor leptons ? (electrons or muons) and a quark-pair jet. A model is considered in which the Image 1 is an excited neutrino in a compositeness scenario. The analysis is performed using a sample of proton-proton collisions at
recorded by the CMS experiment at the CERN LHC, corresponding to an integrated luminosity of 138
. The data are found to be in agreement with the standard model prediction. For the process in which the Image 1 is produced in association with a lepton, followed by the decay of the Image 1 to a same-flavor lepton and a quark pair, an upper limit at 95% confidence level on the product of the cross section and branching fraction is obtained as a function of the Image 1 mass Image 2 and the compositeness scale ?. For this model the data exclude the existence of Image 3 (Image 4) for Image 2 below 6.0 (6.1)?TeV, at the limit where Image 2 is equal to ?. For Image 5, values of ? less than 20 (23)?TeV are excluded. These results represent a considerable improvement in sensitivity, covering a larger parameter space than previous searches in Image 6 collisions at 13?TeV.
