CMS Tracker alignment and its influence on the b-tagging performance

Tagging of b jets is of fundamental importance for the top physics at LHC and only an efficient and aligned tracker detector can offer the possibility to increase the precision in the detection of tagging vertexes. At the Compact Muon Solenoid (CMS) experiment, the alignment of the Tracker is an important goal in the determination of the robustness of the b-tagging algorithms performance: many studies and tests about possible alignment strategies have been carried out during these years, using different algorithms on sets of real (cosmic muon tracks) and simulated data (muon tracks from $Z$ and $W$ decays ).