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T: Fachverband Teilchenphysik

T 53: Electroweak Interactions I

T 53.10: Vortrag

Mittwoch, 17. März 2021, 18:15–18:30, Tc

Measurement of Zγγ production in pp collisions at √s = 13   TeV with the ATLAS detector — •Philipp Ott — Kirchhoff-Institute for Physics, Heidelberg University

The simultaneous production of three electroweak gauge bosons is a rare process predicted by the Standard Model of Particle Physics (SM). The theory predictions of the electroweak sector of the SM can be validated by measuring the cross section of the aforementioned process. The analysis presented in this talk aims to measure the simultaneous production of a Z boson and two photons (Zγγ). In order to determine the cross section of this process, it is crucial to separate signal events from events arising through background processes mimicking the signal topology. The most dominant background is the production of non-prompt photons within jets. Due to the abundance of hadronic activity in the ATLAS detector, such processes have a non-negligible contribution to the total number of events selected in the signal region. A data-driven method is used to determine the non-prompt photon production by exploiting variations in the shape of the energy deposited in the proximity of photons. Templates describing the different energy behavior are used in a maximum likelihood estimation to measure the amount of prompt and non-prompt photon events in the signal region.
After giving a general introduction about the Zγγ analysis, highlighting the motivation and challenges of the measurement, an overview of the data-driven method used to determine the dominant background process is presented.