Philipp Rincke half time seminar- Background estimations for the ATLAS search for Higgs boson pairs in the bbττ channel

Thursday 13 Feb 2025, 10:30 → 12:30 Europe/Stockholm

The shape of the Higgs potential determines the stability of the universe and depends on the Higgs self-coupling, which has not been measured yet. This measurement typically relies on observing Higgs boson pair production, for which the highest expected sensitivity for Standard Model (SM) signals is achieved in the HH → bbττ decay channel.

Several SM processes contribute to this final state as backgrounds. One of the most important backgrounds consists of processes where quark- and gluon-initiated jets are mis-identified as hadronically decaying τ leptons (fake τ leptons), which are difficult to model precisely with simulations. A better description of these backgrounds can be achieved using data-driven methods, such as the Fake Factor method.

This talk will present the Fake Factor method which is under development for the Run 2 + Run 3 HH → bbττ analysis to model the QCD multijet background. The method relies on creating a fake-τ enriched template of events by inverting the τ lepton identification criteria. This template is then re-weighted using Fake Factors derived in control regions to model the QCD multijet background in the signal region, for which the current fake-tau background estimate will be shown.

A summary of my ATLAS qualification project will also be presented in this seminar.