Search for the standard model Higgs boson decaying into tau pairs produced in association with a W or Z boson

A search of the Standard Model (SM) Higgs boson production in association with a vector boson, W or Z, is performed at LHC, using data collected with the CMS detector during 2011 and 2012, corresponding to a total integrated luminosity of 24.5 fb⁻¹. The associated production represents an interesting channel for the low-mass Higgs boson search, thanks to the presence of highly energetic leptons coming from W and Z decays which suppress the most relevant SM backgrounds. The Higgs decay search is performed in the di-τ decay mode, in which each τ can decay into an electron, a muon or hadronically (τh) and a neutrino. The WH channel has three leptons in the final state, with W decaying into electron or muon and a neutrino; instead the ZH channel is performed in a four leptons final state, where the Z decays into a pair of electrons or muons. The data analysed are compatible with the SM expected background, and no significant excess is observed.