Search for the A/H boson in the hadronically tau leptons decay channel

Alexandre Nikitenko, Konstantinos A. Petridis and Stuart Wakefield

Introduction

The MSSM extension of the Standard Model is characterized by the existence of a heavy neutral scalar in its Higgs sector. CMS data will be analyzed in the perspective of finding a signal in the A → tau tau accompanied by two b quarks final state: A bb → tau tau bb. The group has undertaken the development of the tools required to perform this analysis such as the indentification of tau leptons. The extraction of a signal requires also an efficient identification of b quarks as well as missing transverse energy reconstruction. The later can be improved by the use of an energy flow algorithm also developed by the group. This analysis will also be used for the search of the Standard Model Higgs boson in the same final state.

Backgrounds

Along with reconstruction and identification issues, this analysis is facing the participation of numerous Standard Model backgrounds; the production of jets in the final state which constitutes the so-called multi-jet background is the most important one. The multi-jet background will have to be studied with real data but analysis techniques are already been developed with simulated data.

Finding the tau leptons

The particularity of that signal is the presence of two tau leptons in the final states which can be exploited when selecting events recorded by the CMS detector. Information from the calorimeter, the tracker and the pixel detectors are combined to identify the presence of tau induced jets. Once the event is recorded, more demanding constraints are applied to these jets which constitute the tau-tagging procedure.  Its use, results in the suppression of the background.  The identification of the b-quarks is also necessary.

Reconstruction of the Higgs mass

Just as in the search of the Standard Model Higgs (link Maiko), the mass of the Higgs boson can be reconstructed knowing the energy and direction of the tau-jets. In this analysis, various mass windows are been explored in the idea of optimizing the extraction of a signal. The resolution on the Higgs mass depends on the resolution obtained when trying to reconstruct the missing transverse energy (induced by the escaping neutrino particles) and on the precision with which we can determine the aperture angle between the tau particles. Methods of improving the resolution on the missing energy were formulated and based on an efficient way of calibrating the jet energy.

Discovery potential

The present analysis shows that for the discovery of the MSSM heavy neutral Higgs boson would be possible with 10 to 50 fb^-1 of integrated luminosity depending on the mass of the Higgs.