Speaker
Description
A study of the background composition and modelling in a search for scalar resonances in the diphoton-plus-muon ($\gamma\gamma + 1\mu$) final state is presented, using $164~\mathrm{fb}^{-1}$ of proton-proton collision data collected by the ATLAS detector at $\sqrt{s} = 13.6~\mathrm{TeV}$ during 2022--2024 LHC Run~3 operations. Events are selected by requiring two isolated photons with $p_{\mathrm{T}}(\gamma_{1}) > 35~\mathrm{GeV}$ and $p_{\mathrm{T}}(\gamma_{2}) > 25~\mathrm{GeV}$ satisfying Tight identification and FixedCutLoose isolation, together with at least one muon with $p_{\mathrm{T}} > 10~\mathrm{GeV}$, while vetoing electrons, tau leptons, and $b$-tagged jets. A systematic optimisation of muon working points across Medium and Tight operating points is performed. The background composition from $\gamma\gamma$+jets, $V\gamma\gamma$, $t\bar{t}\gamma\gamma$, and single Higgs production is characterised using stacked Monte Carlo simulation, with signal sensitivity evaluated using a $\gamma\gamma+leptons$ benchmark sample. Preliminary data-to-Monte Carlo comparisons show good agreement. The continuum background in the $m_{\gamma\gamma}$ spectrum is modelled with analytical functional forms, and a spurious signal test validates the chosen parametrisation. The current status and prospects are discussed.
| Apply for student award at which level: | MSc |
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| Consent on use of personal information: Abstract Submission | Yes, I ACCEPT |