VHbb Analysis with CMS, an introduction

Abstract

The observation of a new particle with a mass of about 125 GeV, announced in July 2012 by the ATLAS and CMS collaborations, has given hope to the HEP community that the long sought Higgs boson, the last missing ingredient of the Standard Model of Particle Physics, might have been discovered at last. The Compact Muon Solenoid experiment (CMS) is a general-purpose detector installed at the Large Hadron Collider (LHC) at CERN. During 2011 and 2012, the CMS detector has collected over 17 inverse femto-barns of proton-proton collisions (5 fb -1 at √s=7 TeV and 12 fb -1 at √s=8 TeV). These data are currently been analyzed to further characterize the recently discovered Higgs boson candidate. For a Higgs mass of about 125 GeV, the dominant decay mode should be into bb - ; however, such decay has not yet been observed experimentally due to overwhelming backgrounds. A promising channel to search for H→bb - is the VHbb channel, where the Higgs boson is produced via the 'Higgs-Strahlung' process (a virtual W or Z boson with sufficient energy can then emit a Higgs) and recoils with large momentum transverse to the beam-line, to finally decay into a bb - pair (b-jets). The presence of a vector boson in the final state highly suppresses the large QCD background and provides an efficient trigger path when the vector boson decays to charged leptons (e, μ). Recent developments in τ lepton reconstruction and vector boson invariant mass determination made it feasible to extend the VHbb analysis to both leptonic (e, μ) and hadronic (jets) decays of the τ lepton. The current VHbb results are summarized and the novel VHbb final states are presented, with particular focus on HZ, with H decaying to b-quarks and Z decaying to tau electron and hadronic tau.