Final Report Summary - ATLASHIGGS2TAUS (ATLAS Higgs to taus)
In July 2012 the ATLAS and CMS collaborations jointly announced the discovery of a new boson at the Large Hadron Collider. Up to now this new boson is consistent with the so-called Higgs boson, a massive scalar particle predicted by the Standard Model (SM) of particle physics. The goal of this project was to measure the properties of this new particle, primarily its couplings to other particles and its quantum numbers through a suite of measurements. This was achieved by taking a leading role in searches for the Higgs boson decaying to tau leptons, produced in several production mechanisms, key among them the so-called Vector Boson Fusion (VBF). During the course of this project, the proponents contributed significantly to the first direct observation in a single decay channel of evidence for the Higgs boson coupling to fermions.
We also prepared a further measurement in the VBF production mode of the particles CP quantum number, which describes whether its decays are symmetric under exchange of particles for antiparticles joined with an inversion of the spatial reference frame. This measurement utilizes the angular correlations between the hadronic jets characteristic for the VBF production mode. Observation of an asymmetry in this measurement would contradict the theoretical predictions for the SM Higgs boson and could provide hints for new physics beyond the Standard Model. Concurrently with these efforts we contributed to the preparation of the ATLAS experiment for the second data-taking period of the LHC, which at the time of writing this document is imminent. Several contributions, especially to the development and maintenance of the tau lepton reconstruction software used in the above mentioned measurements, were made to ensure smooth resumption of the efforts to consolidate the evidence for the Higgs boson decaying to tau leptons and to measure its properties for the first time in tau-lepton channels.
The work for this project was carried out within the ATLAS collaboration, which is an international collaboration of physicist from 38 countries operating an experiment at the Large Hadron Collider at the laboratory of the European Organization for Nuclear Research (CERN). The results from this project, especially the observed evidence for the coupling of the Higgs boson to tau leptons, has generated widespread public interest.
We also prepared a further measurement in the VBF production mode of the particles CP quantum number, which describes whether its decays are symmetric under exchange of particles for antiparticles joined with an inversion of the spatial reference frame. This measurement utilizes the angular correlations between the hadronic jets characteristic for the VBF production mode. Observation of an asymmetry in this measurement would contradict the theoretical predictions for the SM Higgs boson and could provide hints for new physics beyond the Standard Model. Concurrently with these efforts we contributed to the preparation of the ATLAS experiment for the second data-taking period of the LHC, which at the time of writing this document is imminent. Several contributions, especially to the development and maintenance of the tau lepton reconstruction software used in the above mentioned measurements, were made to ensure smooth resumption of the efforts to consolidate the evidence for the Higgs boson decaying to tau leptons and to measure its properties for the first time in tau-lepton channels.
The work for this project was carried out within the ATLAS collaboration, which is an international collaboration of physicist from 38 countries operating an experiment at the Large Hadron Collider at the laboratory of the European Organization for Nuclear Research (CERN). The results from this project, especially the observed evidence for the coupling of the Higgs boson to tau leptons, has generated widespread public interest.