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T: Fachverband Teilchenphysik

T 55: Bosonic and Rare Higgs decays

T 55.1: Vortrag

Mittwoch, 17. März 2021, 16:00–16:15, Te

Background Modelling in the ATLAS H→γγ Differential Cross Section Analysis — •Nils Gillwald — Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany

Since its discovery in 2012, efforts to measure the Higgs boson properties as precisely as possible are ongoing in order to probe the Standard Model of particle physics and look for potential deviations from its predictions. Differential cross section measurements are an important part of these efforts. They aim at providing model-independent differential measurements of different kinematic and event observables, offering access to e.g. properties of perturbative QCD, the spin and CP nature of the Higgs boson, bottom and charm Yukawa couplings and potential new heavy particles coupling to the Higgs boson. This talk focuses on an analysis in the H→γγ decay channel, using the full Run-2 data set taken between 2015 and 2018.

The general measurement strategy uses a signal and background fit to data to extract signal and background yields, which are then unfolded to particle level. For this fit, a functional form describing the background distribution needs to be determined. This is done based on Monte Carlo simulated templates. The potential bias on the measurement due to the choice of the background model is the largest systematic uncertainty in the fit procedure. This uncertainty is called the spurious signal uncertainty.

In this talk, the H→γγ differential cross-section analysis is discussed with an emphasis on the background modelling strategy and the resulting spurious signal estimate.