Measurements of the $W$ boson resonance at LEP2

The amazing series of experimental discoveries and ingenious theoretical insights of the last century not only profoundly changed the way of our understanding of Nature, but allowed for a relatively simple and unified description of laws governing the processes we observe. The Standard Model of elementary particles arose from this fruitful collaboration between experimental and theoretical researchers. During the late '60s and eraly '70s it was formulated into his final framework, with the prediction of at that time yet undiscovered particles. Among them the W boson, which is one of the most essential particles for electroweak interactions. This thesis presents measurements of the W boson resonance, which is mainly characterized by its pole mass and width. The data accumulated by the DELPHI experiment in e+e- collisions at the LEP machine was used. This experiment provided symmetric collisions of electrons and positrons recreating at a microscopic scale the physics which prevailed about 10^-11 seconds after the Big Bang. The W boson parameters were inferred from the W+W- events where both W bosons decay hadronically. This data set contains about 35% of the full statistical information available in e+e- collisions on these quantities. This book is structured to aim for a thorough and complete overview of these W boson measurements, including all relevant phenomena related to W+w- events.