Light Non-prompt (Fake) Lepton and Di-boson (VV) Background Estimation with a Template Fit Method for HH Production with a Signature of Two Same-sign Electrically Charged Light Leptons Associated with a Tau Lepton

The search for di-Higgs boson production HH probes the tri-linear coupling HHH predicted by the Higgs mechanism. In this search with two same-sign electrically charged light leptons and one hadronically decaying tau (2ℓSS1τ channel), the tt¯ and VV backgrounds are dominant and the estimation of these backgrounds by a data-driven method is studied. For the data-driven background determination, the Template Fit method is used. The resulting normalization factors for fake light leptons from heavy flavour decays are 0.82 ± 0.03 for muons and 0.93 ± 0.09 for electrons, and 0.85 ± 0.05 for VV production