Optimierung der Photonenselektion für die Suche nach dem Zerfall des Higgsbosons in zwei leichte CP-ungerade Skalare

In some extensions of the Standard Model, extended Higgs sectors are postulated, from which, in addition to the Standard Model-like Higgs boson, a new CP-odd scalar arises. If this scalar’s mass is small, final states consisting of two photon pairs would be generated by the decay of the Higgs boson into two of the above mentioned scalars and the subsequent decays of the scalars into photon pairs. In the ATLAS detector, such a pair of photons would be reconstructed as a single photon. In order to analyse the data generated by the ATLAS detector at the LHC, one needs to know the efficiency of the photon pairs to be identified as a single photon. Using Monte-Carlo simulations, this identification efficiency is calculated and analysed for several photon selections and for three different masses of the scalar in the mass range of 100 to 400 MeV. This leads to the creation of an optimized cut menu for this final state. The aim of this is to make the analysis of the ATLAS-generated data with regard to this special decay possible. Furthermore, the conversion rate of reconstructed photons arising from the decay of the Higgs boson into the scalars is compared to the conversion rate of reconstructed photons coming from samples of direct photons as well as to the conversion rate of reconstructed photons coming from the jet underground.