Implementation of position and angle uncertainties in the muon reconstruction of the CMS experiment, and impact on the performance

The alignment of muon chambers relative to each other and to the inner tracker is crucial to achieve the optimal performance of muon reconstruction at high momentum, in particular the best possible momentum measurement. With the energy and luminosity increase in LHC Run2, the high momentum muons have become more important for the searches of new particles with masses around the TeV scale. The muon reconstruction of the CMS experiment has been recently improved and made more robust with the introduction of alignment uncertainties on the positions and angles of the segments in the muon chambers. Not only does the momentum resolution improve at high energy, but, owing to the better quality of the muon track building and fit, also the trigger efficiency increases, especially in the initial phase of data-taking, after the opening and closure of the detector.