Systematic effects of background parametrisation in the search for dimuon final states with the CMS detector

Modern physics largely relies on the power of colliders to investigate the fundamental aspects of nature. The search for new particles often implies looking for a resonance over a continuous background and it is essential to know the background's shape with high accuracy in order to detect a possible signal. In this work the impact of the background modelling on the signal yield is investigated. This is done by calculating the bias associated with an incorrect choice of the background function and how this systematic error depends on the collected luminosity. Fits are done using different functions in chosen mass ranges and for different values of the luminosity. The data used are from the dimuon invariant mass spectrum as detected by CMS during the 2016 Run2 of LHC and from Monte Carlo simulations.