Studies of possible background processes for the search for the heavy neutrino originating from the D+s - м+N - м+м+п- decay using CMS experiment data

We report the studies of possible background processes which could contribute to the signal region in the search for the heavy sterile neutrino originating from the D+s - м+N - м+м+п- in the CMS Experiment at the LHC (CERN). The D+s - п+п-п+ decay is investigated as well as the intermediate resonance structure of п+п- system, also studies of different decay modes involving K0s и Л particles are reported. Such channels could provide background contribution in case of misidentification of tracks as muons. The paper uses data collected by the CMS detector in 2018 year in pp-collisions at the LHC at s = 13 TeV, corresponding to integrated luminosity of 60 fb-1.