Search for lepton-flavour violating decays of Higgs boson at the LHC with the CMS detector

Jan Oliver Rieger
Oct 2013

Thesis Type:

This thesis deals with lepton-flavor violating decays of the Higgs boson, especially the production via vector boson fusion and decay into a muon and a tauon are considered. Therefore the data used was collected in 2012 with the CMS detector at the LHC. The essential challenge was a reduction of the standard model background by an optimized analysis in order to discover this decay or to determine a new upper limit on the existing branching ratio BR$(H \to \mu\tau) \approx$ 10%. The analysis uses rectangular cuts for four specific observables tailored to the VBF production mode. In particular, a significantly improved mass reconstruction leads to a clearly reduced upper limit on branching ratio of the Higgs boson decaying into a muon and a tauon of BR$(H \to \mu\tau) \lt 3.9$%.