Packaging and assembly technologies for the pixel detector upgrade and measurement of $\tau\tau$ final states with the CMS experiment at the LHC

The work, performed in the context of the CMS experiment at the LHC, is related to the assembly of the future CMS pixel detector and to improvements in the identification of hadronically decaying tau leptons. The performance of the tau identification has been evaluated in the data collected by CMS in 2015 and a measurement of the inclusive Z production cross section at 13 TeV has been performed.