The work presented in this thesis spans a wide range of experimental particle physics subjects, starting from level-1 trigger electronics to the final results of the search for Higgs boson decay and to tau lepton pairs. The thesis describes an innovative reconstruction algorithm for tau decays and details how it was instrumental in providing a measurement of Z decay to tau lepton pairs. The reliability of the analysis is fully established by this measurement before the Higgs boson decay to tau lepton pairs is considered. The work described here continues to serve as a model for analysing CMS Higgs to tau leptons measurements.

This thesis presents a search for the standard model Higgs boson decaying to a [tau tau] pair using CMS data recorded at the LHC with 7 TeV and 8 TeV center of mass energy during 2011 and 2012 respectively. The search is performed using two channels [tau mu tau eta] and [tau epsilon tau eta] where [tau epsilon, tau mu] represent a [tau] decay to an electron or muon and [tau eta] represents a [tau] decay to hadron(s). The search is performed in the range 100 GeV

A search for neutral MSSM Higgs bosons in pp collisions at the LHC at a center-of-mass energy of 7 TeV is presented. The results are based on a data sample corresponding to an integrated luminosity of 36 inverse picobarns recorded by the CMS experiment. The search uses decays of the Higgs bosons to tau pairs. No excess is observed in the tau-pair invariant-mass spectrum. The resulting upper limits on the Higgs boson production cross section times branching fraction to tau pairs, as a function of the pseudoscalar Higgs boson mass, yield stringent new bounds in the MSSM parameter space.