Higgs in bosonic channels (CMS)

Valentina Gori

doi:10.1051/epjconf/20159504026

Abstract

The main Higgs boson decays into bosonic channels will be considered, presenting and discussing results from the latest reprocessing of data collected by the CMS experiment at the LHC, using the full dataset recorded at centre-of-mass energies of 7 and 8 TeV. For this purpose, results from the final Run-I papers for the H → ZZ → 4ℓ, H → γγ and H → WW analyses are presented, focusing on the Higgs boson properties, like the mass, the signal strenght, the couplings to fermions and vector bosons, the spin and parity properties. Furthermore, the Higgs boson width measurement exploiting the on-shell versus the off-shell cross section (in the H → ZZ → 4ℓ and H → ZZ → 2ℓ2ν decay channels) will be shown.

Highlights

1 Introduction After the Higgs boson observation in 2012 by the ATLAS and CMS experiments [1, 2], the main goal for both the collaborations is the precise measurement of its properties exploiting the growing statistics, in order to confirm or to find discrepancies with respect to the standard model (SM) predictions for the Higgs properties themselves
Direct measurements of the Higgs boson width performed in the H → ZZ → 4 decay channel result to be strongly limited by the detector resolution, do not allow to give a useful constraint on the resonance width
The analysis of Higgs boson decays in bosonic channels has been crucial for the Higgs boson discovery and is important for mass and properties determination

Summary

Introduction

After the Higgs boson observation in 2012 by the ATLAS and CMS experiments [1, 2], the main goal for both the collaborations is the precise measurement of its properties exploiting the growing statistics, in order to confirm or to find discrepancies with respect to the standard model (SM) predictions for the Higgs properties themselves. EPJ Web of Conferences at the LHC [3] This channel has a very low branching ratio (BR ∼ 10−4); it was the “golden” channel for the Higgs discovery, because of its high resolution (only leptons, fully reconstructed final state) and high signal over background ratio. The reconstructed Z boson masses and five production and decay angles are used to build a kinematic discriminant using matrix elements at Leading Orded to separate signal from background. This technique is known as “MELA” (Matrix Element Likelihood Analysis) and can be used to build a discriminant aimed at the determination of the spin-parity properties of the resonance, or its width.

H A ZZ A 4e H A ZZ A 2e2 H A ZZ A 4

Mass combined measurement

Findings

Conclusions